I looked at the ee code and when vin is updated, it is written straight with no eeprom registers involved. Might be unlocked on default.

ldx #$1994
ldy #$E24
ldaa #$11
And than updated in a loop with no delays or whatever.

I think in ee[tside for sure] you can write to eeprom as a standard write to ram routine. Might give a try with some small test region.