Here are the instructions I followed:
Full Update Guide - Rogers Dream EBI1 to CyanogenMod - CyanogenMod Wiki
Specific to our Rogers phones and maintains the Rogers radio as well... As long as you don't need Exchange contact and calandard sync then you are good to go... Mind you there is a free contact sync app in the market already, so really only the calandar was an issue.
Since I use my phone for buisness and we have an exchange server I actually reverted back. It's really simple to do that with either a nandroid backup created before you update:
XDADeveloperWiki - HTC_Sapphire_Hacking_2
Or even simpler just install the 1.5 update from Rogers web site:
Just need to read the instructions and follow allong...