Alright, IIRC, in the early versions of the Soundfont loading interface (read: SBAWE32/64 control panel), you had a button that let you pick which card's synth the control panel would control, assuming you had more than one AWE-type synth in there (example: AWE32+WaveBlaster daughterboard?); however, the button was still there even if you had only one card.
....ANYWAY, there should be an equivalent button for the Live!/Audigy's "AudioHQ" program, somewhere. Click that, and then you should have a box where you can select the card. At that point (assuming it works exactly like that of the one used by the AWE control panel), there should be a checkbox that says "Allow Wavetable Synthesis Only"....deselect that.
With me so far? Good. Now, here's the easy part. Go to the Start Menu, and open Control Panel, and open the "Multimedia" applet (or whatever its named in versions of windows that are later than Win98SE), and go to the MIDI tab (or equivalent dropdown box, IIRC), and select "Creative Stereo Music Synthesizer"....and you're done!
Now, whenever you try to play a MIDI file, it SHOULD use the card's FM synth chip to do it.