We will use the joypad code 001B2D82 that we got from Twisted Metal 2 to illistrate here.
When 001B2D82 is equil to the value of FFBF then we want it to add a decimal value 6 to the value of the code 00187D00. It is possible to subtract too. Just change the add to a subtract. Now when we press the X button the Infinite Armor code is adjusted by 6. Generate the code to see it.
Yup, that's a lot of codes. I have yet to figure this one out yet. :-)