What have you done so far to make the conversion happen, we can't help people that haven't shown that they know how to help themselves. That's no simple thing to convert an entire module to a different chip and you may not be able to do it at all depending on pin compatatbilities, you'd also have to completely rewrite the code from scratch.
Why you wonna do that.
I think that Thing works fine with an ATMEGA 8 Controller.
The Source Code you see is only the Main program of the ATMEGA8.
You also must convert the remote.c and the remote.h file for the PIC.
I think Sceadwian is right. It's easyer to develop new Code for a PIC.