Diki, the codes for the G/E series and BKs are the same, they are the first thing I tried.

According to owners manual for the BK7m, to recall a "Performance Memory" (formerly known as user program), send a program change on the basic channel to CC00 = 7AH (decimal 122) and I just used CC32 = 00H in an attempt to address a User Program between 1 and 128. No joy. As you mentioned, higher values of CC32 allow you to access the subsequent "pages" of performances.

I'm starting to think that this functionality isn't possible on the Prelude. There IS an ability to assign EITHER "Performance Up" OR "Performance Down" to the footswitch. It works, but there's nothing in the recorded MIDI to suggest a corresponding SysEx string or Program Change. When Roland published OS version 2 they added the ability to directly recall style variations and fills via MIDI message. But nothing about recalling user programs, nor a "basic" channel to receive such messages. Hmph.