reverting back to 2.10 from 2.13 - any help?

[steve austin]

I am finding that the touch response - even with tweaks - is too much for me to get pass at the moment. I would like to finally flash to a custom ROM. The problem, if I am reading right, is that the new t-mo upgrade (2.13) will not allow you to flash. You have to revert back to the ROM that came with it out of the box (2.10).

Can anyone tell me - step-by-step how to do this? I have tried to find help in this area but some of the answers led me down a very vague place. any assistance would be greatly appreciated.

Note: If I am incorrect, and I don't have to revert back, then let me know so I don't wast my or your time.