Get your save A off your USB or HDD, and BACKUP then DELETE the B file!!
Open your A save in the editor
Enter desired amount and press Save. *See note about "Max Money"
Rehash and Resign in your favorite program.
Move back to USB or HDD
Load Save - Profit!
A note on "Max Money" If you have 0 - 255 then 255 is max then 256 - 65,535 then 65,535 is the highest you can go, Earn some more money in game then open your save again and you should be able to mod to 16,555,444.
If you have any problems please upload your save and say how much money you have, be sure you are searching for the correct amount of money!