Hi,
The CODM (Custom Organ Design Module) references wave files - so if you wanted to use samples from a soundfont you'd first either export them from the soundfont, or create recordings of the rank from soundfont - this may create a better result as the soundfont has attack sustain delay and release paramters for each note, so the exported wave file from a soundfont might not sound like what you hear when playing the note.
Once you have your wave file for each note (or each second note, third note, or whatever) from the soundfont, then you must name them in the HW expected format of 036-C.wav, 037-C#.wav, - 096-C.wav, etc. You must also add loop markers for the sustain section, and release markers. There are various tools that help you do this.
It might be simpler to experiment in another organ sampler platform that supports soundfonts natively.
GrahamG