Good luck with that. There are no service/hardware manuals as far as I'm aware.
See my posts in
this topic to get started on disassembly. If you wanted to see the manual for compatible CPUs, I suggest looking into the
datasheet, or asking users with U9200 here or on other forums to run CPU-ID or similiar software. (Note: the datasheet doesn't list T7400. Then again, it also doesn't list T5450, which came with my laptop and definitely works so YMMV) If
Wikipedia is to be believed, there aren't many variants of "T7400" or whatever you'll find in the datasheet, typically boiling down to different sockets and (rarely) different steppings. You should rely on the
Intel CPU finder though.
Disclaimer: I have zero experience with upgrading CPUs in laptops.