I've tried the Frequency setting, it doesn't seem to impact VRAM usage unfortunately. Changing the CPU allocation factor also wouldn't do anything, that just changes the amount of CPU time the BOINC Manager thinks a work unit uses, not what it actually uses.
I'm worried about possibly crashing the NVIDIA drivers if I tried to run multiple different compute applications at one time, so I don't think I'll try to crunch foldingcoin/curecoin simulanteously.