I still do not get exactly what you want, but here is a guess:

one_of_eight ds 1
one_of_three ds 1

mov a,one_of_three
rl a ; multiply by 8
rl a
rl a
add a,one_of_eight
mov dptr,#table
movc a,@a+dptr
value in a

table db ..........

the contents of the table should be for
3=8=

0 0
0 1
0 2
0 3
0 4
0 5
0 6
0 7
1 0
........

Hope this helps,

Erik