If v_cal is 1023 (maximum 5.000V) it's correct this command for memorise in EEPROM :
write 0, v_cal
...
read 0, v_cal ???
It's enough like these or need more ?
If you have PBP 2.60, then you could ...

Code:
write 0, WORD v_cal

read  0, WORD v_cal
If you don't have 2.60 yet, you'll need to ...

Code:
write 0, v_cal.LowByte
write 1, v_cal.HighByte

read  0, v_cal.LowByte
read  1, v_cal.HighByte