Here's a Hex to Int conversion function I found in my old code:
FUNCTION HexToInt%: hex$
LOCAL i%=0
LOCAL j%=0
LOCAL loop%
FOR loop = 0 TO LEN(hex$)-1
i = ASC(MID$(hex$, loop, 1)) - 48
IF i > 9
DEC i, 7
ENDIF
j = j * 16
j = bOR(j, bAND(i, 15))
NEXT
RETURN j
ENDFUNCTION
[Edit] Ha, apparently I got my code from MrTAToad in that link posted by dreamerman!