I just did this to my desire to install the cyanogenmod ROM.
First, root your phone here:
(After backing up of course).
Then you WILL need to do the HBOOT fix to unlock the phone, because security is still on at boot (s-on) (http://alpharev.nl/)
Following the instructions here:
Is wise 😛
Now I have a happy Modded phone, without all the HTC/Google stuff running in the background, which I can then install as I want.