I'm not aware of any documentation on the SCSP DSP (which is probably what gets used for those effects) either. It's possible that only the SGL developers had "real" documentation.
edit: should have said the SCSP DSP instruction set... there is a block diagram in the SCSP manual, and it says where the instructions should go, but IIRC has zero information on the actual instruction set, which is sort of the important part.
(Edited by ExCyber at 4:20 am on Jan. 25, 2002)