If you like tinkering it is possible. I remember seeing a 22RE in an RA65 once, turboed on the stock ECU, and maybe different injectors and AFM. Also I know of a turboed 3T using some form of Datsun ECU (from memory).
Though if you enjoy driving the thing more than lying under it, an aftermarket computer is a very good idea. It makes it heaps easier to get everything running with the random engine parts you can scrounge up.
If you are looking for more info about turboing it there is an incredibly huge thread on Toymods about turbo 18RGs.
Hen
EIDT - Another idea for a cheap, programmable ECU is Delco. You can pinch them from EFI Camiras?? and they are remappable and there seems to be a bit of support for doing wild things with them