Well I've been able to dig up some information on the 24-hole tremolos here:http://www.ehow.com/how_6404738_play-24_hole-tremolo-harmonica.html
Some more on the Bee Chinese ones:
And still yet even more information on their layouts:http://en.wikipedia.org/wiki/Tremolo_harmonica
I'm thinking the answers for you have to be here somewhere.
Also, being a guitarist, you should probably have a chromatic tuner, eh?
If so, with tuner on and in hand, play the first two notes on the lowest holes. I believe the blow note(s) will be the key of the harp!
Hope this helps!
Keep us posted!
Keep on (tremolo) Harpin'!