I'd follow this thread : http://forum.androidcentral.com/htc-evo-4g-rooting-roms-hacks/35955-evo-hdmi-out-mirroring.html
There's a guy working on it, for both Sense and AOSP.
He was at xda but do to conflicts, he moved to AC. That's the thread he told me to follow.
He's also already taken in...