Well, yes and no.
Yes (in theory) you can use a MIDI footpedal to controll things on SX900 but not as many things as you can control on Genos.
SX900 for instance, does NOT support MFC 010 foot controller and compatible devices.
Have a look a the data list manual to see what is available on SX900 for control by MIDI.
I found it not enough to actually go for a MIDI footcontroller on SX900 (which I do use on Genos)
Best Regards
Rudy