You can - what it looks like, and I say that because there's a lot of "speculative" threads and then threads with details and then tested things, it's hard to sort out really. What it looks like is EVOs with 2.02+ hboots have slightly different sized recovery and boot partitions, so the boot would effect some kernels. It's probably why after downgrading to hboot .76, you can't load a rom without re-installing it through recovery. (edit: this is what I tested today, on 003 hardware my partitions did in fact change with the installation of hboot 2.10) So it really depends on the kernel and if it will fit in to boot.
If I were you, I would root with this:
[ROOT] ~~~ HTC EVO - Universal Auto Root ~~~ v1.9.4 (12/22/10) - xda-developers
Then once you're up and rooted, I would downgrade my hboot to .76 or .97 or something more friendly, install clockwork if that's your favorite right after that via a PC36IMG.zip file then I'd boot right to recovery, erase all user data, format boot, system, cache, sd-ext, data, dalvik and then I'd install whatever rom you wanted to.