Changing the OTP/UEM on P800

Hey Boys and Girls, my first post :p
I've looked around on the web and found a few rescources for changing the OTP/UEM on mobile phones, mainly nokias, I was wondering several things.

1) Can it be done on the P800
2) Can you use ANY OTP/EUM? Are they universal? IE can I use a nokia OTP/EUM for a Sony Ericcsson?
3) If not can someone tell me where I can find the chip and tools neccessary
4) Can someone provide a guide / Walkthrough for this task?
5) Any help would be GREATLY appreciated.
Thanks
:):D

I can change Imei £20 a handset non UK only