What I have so far:

c=1/7(/13?)
v=2/8(/14?)
x=3/9(/15?)
%=4/10
key=5/11
8=6/12

Take your key.
Example: key x 8 key % key c x
or
53654513

Take your target
Example: c c 8 key 8 v % 8
or
11656246

The first number of your key is 5, the first of your target is 1.
Using the numbers one through six:
1
2
3
4
5
6

cycle through from five to one. Count "six, one." This will give you 2. Write that down.
The second number of your key is 3; of your target 1. Count "four, five six, one." That gives you 4. Write it down beside the two. Keep doing this until you get to :

24662333

We'll call this your code.


For every verticle column, you will have to add three DIFFERENT numbers (ie, NOT 1 + 1 + 1 =3) to get the relevant number in your code. When you get the right number in the code, it will be identical to the symbol you want in that place in your target. Remember from above that v=2 OR 8. So for your first column, obviously you cannot add three distinct numbers of 1 - 6 and get 2. You have to use 8.

Your choices are:
1+2+5
1+3+4
(Am I missing any? I'm not actually good at arithmatic.)
If you put in for your modifiers one that starts with c (1), one that starts with v (2), and one that starts with key (5) your target symbol will be what you want it to be. Same with the second set of numbers. This works all the way across the row for every vertical column.

However, this is where I get stuck. I can get up to having the first two or three numbers of the result identical with the first two or three numbers of the target. However, I get bogged down in the combinations and can't get any further.

Suggestions?