The Losi radio would work, but you wouldn't be able to shift it into reverse because the Losi radio is only 2-channel. You need a 3-channel radio. Something like the Airtronics MX3-FHSS or the Futaba 3PM or Spektrum DX3S/R.

The radio comes with a receiver, so you replace the receiver in your Slayer with the new receiver, bind it, and then set up all the adjustments on the radio to work with your car.