Yes, this idea might work.

My problem is that I do not know the details of the I/O signals of the various parts of these 'bots. With LEGO RCX the outputs to the motors come directly from the encapsulated microcontroller system. The motors are not as powerful as those in a RC car. The commands available to the RCX from the ROBOlab program have seven levels of power.

The RC cars, on the other hand, are driven by a 7.2 volt battery pack through a box called a "speed control". Speed control gets its signal directly from the RC receiver. I think it is treated as a servo. Is this pulse width modulation?

I am hoping to borrow an oscilloscope soon.

Ken