Yes, you can. I bought an aftermarket kit to put into a Hilux that did not come with the cruise. There is a magnet which you need to glue onto the rear drive shaft and a pickup signal coil is then mounted next to it on the body. This picks up pules to inform the cruise controller unit and maintains the speed.
The cruise control manual lists bunch of ECU's and corresponding speed sensor wire to tap in if you have an ECU in the truck. The magnet method is for a car without an electronic speed sensors.