Punto Mk2 8v engine ECU replacement?

I've narrowed down the engine problem on my 51 plate Punto 8v to the ECU. I can buy a new one from Fiat for £352 and fit it myself. I've been told the programming of ithe ECU is quite simple but do not know the exact method or process involved in programming it. I'd appreciate advice / programming instructions. I've also been offered an alternative of a reconditioned ECU but am wary of going down that route, as I'm told it may require replacing locks and ignition switches. HELP!