Look'd into doing it myself before, but only a few phones you can do urself really.
If its possible you'd proberly have to "Flash" it. =/
The best way would be to phone up orange and make up an story about you needing the phone to be unlocked so you can use it with your.. erm Spanish or Turkish Sim card when you go vist family etc.
You need a data cable for your phone and some software... Mate used to do it years ago.
Alternatively, there are small devices powered by batteries that you can stick in the back and it does everything for you. I'll ask my buddy but it was some time ago when we were in college and things will have changed!
i have a 7610 myself,i have unlocked a few phones with them unlocking programs but the newer phones these days have to be unlocked by the network its locked to.