This is the simplest method to remap the function of one key to that of another key.
d::c ;*1 o::a ;*2 g::t ;*3 end::exitapp ;*4 /* 1 Remaps the letter d to the letter c. 2 Remaps the letter o to the letter a. 3 Remaps the letter g to the letter t. 4 Emergency shutdown. */
As long as this script is running, whenever you type DOG you will get CAT. Of course you will also get TAC when you want GOD, but you can't have everything.