The problem with flashing this onto carts would be transferring data off of it. I don't really think you can unless you have some dev tools. It's just like with a blue EMS cart and LSDJ, if you don't have some sort of transferrer, you're fucked!
I'd cough up the money for a powerpak just because it'd save a lot of time and hassle!
Either that or buy a USB gamepad and use an NES emulator, that's about as close to the real thing as you'll get.