VSC is the Vehicle Stability Control System. That is not what you are describing. You are describing the TRAC system which will apply individual brakes and cut engine power during wheel slippage. (in 4LO with A-Trac engaged, the individual brakes will be applied but the engine power will not be modulated).
You can install a switch to control both TRAC and the VSC. There are many threads about these items. Here are but 2 of them.
Install of VSC cancel switch - Toyota FJ Cruiser Forum
disable traction control? - Toyota FJ Cruiser Forum
DEWFPO