Yeah you can possibly make your own. Basically my comment of changing the PATs chip from blue to red refers to a little glass tube within the key. The older 3 button tibbe key that the earlier mondeos, fiestas, KAs, transits, Puma etc have are known as red ones and can only be programmed to the corresponding receiver within the car. Later cars such as the later models of some of the aforementioned use a blue chip and can't be programmed to car which which is listening for the red chip.
If you get one of these keys with a flat blade it'll 99.9% likely have a blue chip. You can replace this with one from one of your spare keys but it will mean butchering it slightly to get it out. You then need to find out how to replace the flat blade with a tibbe one, something I've not tried to do.
As for swapping an IR system for an RF system I don't recall anyone doing it although it has previously been discussed. If you go ahead and get it working you could always create a guide as I imagine it might interest a few other people.
Hope this helps.