I'm trying to make some custom patches/sounds using Emagic's SoundDiver or Midi Quest XL. Fun, right? I say yes!

Well, I have my MT-32 hooked up as the 2nd device in a chain with my SC-55 as the first, and the MT-32 is connected from the midi-thru of the SC-55 into the MT-32's midi in. This all works dandy cause I can mute the SC-55 and the MT-32 plays gloriously in all DOS games. Great stuff.
I figured out I had to connect the midi-out from the MT-32 directly into my PC rather than it being passed through midi-thru. The Default instruments will now dump to the PC via sysex.
My problem lies in when I'm editing patches or just trying to play my MT-32 via an external keyboard (A Roland PC-200 MK II).
The keyboard is hooked up to my SC-55 via the front midi-in port. It plays the SC-55 perfectly. If I hook the keyboard up to my MT-32's midi in, it plays _it_ perfectly. What I want to do is have the keyboard hooked up to the SC-55's front midi-in, and then route the keypresses through the SC-55's rear midi-thru to my MT-32.
According to the SC-55 manual, it should do this by default.
Yet, try as I may, I can't get my MT-32 to play any notes. I've even tried changing the transmit channel on the keyboard from 1 to 2 to no avail... Any ideas?
See, the purpose in all of this is to be editing instruments in Midi Quest, then use my keyboard to play a note, well, hold it down while tweaking things like pulse modulation, LFO etc. and hear it happening realtime. You can't really know what you're going to get unless you do this. So, have it kinda act like a pseudo analog turn the dials setup. Kinda.
Any ideas here to get this to work via the SC-55 front midi in with my keyboard?
Thanks.