I am not a professional player and have no pretences in that direction. However, at exhibitions and in my workshop I regularly meet Boehm flute players who have never played a baroque flute but would like to try or would like to buy. I have by now a standard system to give them a beginning.
So maybe it is some information for Boehm flute players interested in the baroque flute or even adapting to the requirements of the instrument to read what I normally advise.
Lets take it step by step.
First of all hands are different. So you have to find out what is best for your hands.
Boehm flute players are used to a b♭ key for the thumb. If the thumb is in a similar
position on the baroque flute the third hole may be more difficult to reach if you do not have big hands. Even if you have big hands the flexibility for the third hole may not be too good. So we have to do what Quantz says in the bible for baroque flute players: have the thumb in the position opposite the middle between the first and second finger. It should also be sticking a bit past the flute. How much really depends on your hand. I have the player let the flute rest on the three fingers on the holes hanging on an outstretched downward arm, totally relaxed. The thumb as indicated above. The arm completely relaxed. Some find this difficult. Bring the flute embouchure to the mouth, usually the position then is very good. The right hand is less difficult but also there the thumb positions should get some attention.
A different point is the distance of the fingers to the holes. Closed hole Boehm flute players are used to have the fingers as close as possible to the keys. However this has a strong influence on the intonation if done on the baroque flute. About a finger thick distance is needed on the traverso.
A subject with many different views. Even in the low lands, Holland and Belgium this is the case.
Bart Kuijken has a story of breath that goes as follows. You have two kinds of breath, one used for blowing out a candle, the other for warming your hands in the winter. For a Boehm flute you use the first for a baroque flute the second. It means that you think less in projecting forward by blowing and more in resonance inside the body for making a tone. I found that sometimes this gives the misunderstand that players think he means sort of a hollow aaaaahhh. That is of course not the case. It just means don't think in blowing, think in resonance.
In my philosophy the way you think has an essential influence in how you make a sound. So I would say thinking in a thin air current is good. But a thin air current with much inside resonance can make a loud tone. This is the struggle of the baroque flute player in many cases.
A basic test for the breath quality for me is the following. Play f in the first octave. If played with the proper resonance it is a nice tone and on my flutes practically well tuned. Playing it by just blowing gives a thin hazy tone that is too high and only by much compensating in tune.
To find what resonance means one should go to the singers world and there one can find all the information. It would be too much to start here trying to describe that.
A simple one is the following. Boehm flute players are used to having the embouchure in line with the finger holes. Quantz says to have the upper edge of the mouth hole in line with the middle of the finger holes. However, many adapt this to there own wishes. But I think that most baroque flute players have the head turned inward to some extent.
Further, embouchure I find the most difficult subject.
People have such different embouchures that it is hardly possible to say anything in general about it.
However, it is clear that the flutes embouchure is smaller then the Boehm flute embouchure. So not to have false air that should also be the case for the player. I think in my rabbits lip muscles but if you don't know rabbits that probably has no meaning.
The somewhat stretched lips that are often used on Boehm flutes is not very functional on a traverso. The lips can be relaxed. I believe however that this is also a discussion point for the Boehm flute but for the traverso it is not. One might think in a standing letter O for the form of the embouchure. Not that this really is the form but it might help compensate the horizontal slit appropriate for the Boehm flute.
A separate issue is the embouchure sweet point. Boehm flute players are used to a large flute mouth hole so they can cover it quite a bit. For the traverso this is a sensitive issue. Different traverso have a different embouchure sweet point. The way to play also depends on the player but less. So how far does one cover the embouchure and under which angle does one play the upper edge.
In any case Boehm flute players easily cover the mouth hole too far. What I have them do is the following. Turn the traverso such that the upper lip feels the upper edge of the mouth hole. Then turn it away to play. This usually gives a reasonable starting point.
Projection versus body resonance.
Again, difficult. In my experience most Boehm flute players think in projecting the tone with force. On a traverso that works like any original this is punished. One does not obtain a nice tone and for a number of tones it simply kills the sound. As mentioned above one should instead think in forming the tone internally in the mouth and body. Though this should be done without any tension! A good tone to use as a test case is again the f1. Pushing normally kills this tone.
 J.J. Quantz, On playing the flute, second edition, Faber and Faber, ISDN0-571-18046-9, different facsimile and translation editions. E.g. ISDN3-7618-0074-6 (and a number of other facsimiles, e.g. in Dutch, in German(original) and in French)