Depends on the type of fuel system you have. If it has a carburetor or throttle body (TBI).  Dump a small amount of transmission fluid down the throat of either system. You will need to keep the vehicle running. Dumping to much fluid at once will stall the engine. Once the fluid has been put in, watch your suspected area smoke will come out from the leak. If it is fuel injected (EFI,MPFI,SFI,TPI or CPI on some trucks) the transmission fluid will have to be sucked in through a manifold vacuum port. If you've never done this before. It would be best to have someone work the gas pedal for you, to keep it running. An experienced mechanic can usually do it alone. I suppose though if you were experienced you wouldn't be asking the question.

Take care, Have a good day and GOD BLESS!