As Julien says, midi could do this easily.
So if you :
- add a midi plugin (the infamous mindi - MOD Devices) that send a PC-5 message (for example) to the midi output
- cross the checkbox of the new “Virtual MIDI Loopback” option to send every midi message getting out of the moddevice back in it (like if it was another midi input)
- you can assign a footswitch to the midi plugin and name it “snapshot 5”
I think you get what you asked, a bit triky though !