No I'm not an idrum user but I do find things that I think may be of interest and report them to the forum.
I've downloaded idrum again to see what I can come up with. I think I know what you're asking and here is the scoot way of doing it. If this is not what you're wanting then I misunderstood the question. I'll write 2 messages for 2 different methods.
Import your drum track into Metro and choose a drumset that matches your import (you you click on the snare you hear the snare etc).
In my example I used GMidiKit.
Open up the 'Drum Sets...' and select from the popup the set you're using.
Note the numbers alongside each drum in your track.
In mine 36 = Bass Drum-2 and 38 = Snare Drum-2
Install idrum onto the track and install the sounds you want to use on it.
Then click the 'i' info button I have highlighted yellow and choose the idrum's Bass Drum you're using and change it's popup number to 36 as in the picture. I'd already mapped the KOTOR Snare.aif to 38.
Match all your other drum sounds and then idrum with play the correct sounds on the metro track.