That is the beauty of android. Cyanogen mod ("open source operating system") doesn't give you access to carrier IQ because it does not have carrier IQ. When people say rom for an android phone it is the firmware.
Just to give you an idea of the crap that comes on a stock phone, the stock rom for my phone is around 400 megs. Cyanogen for my phone is around 90 megs, and has more functionality.
I'm still confused, but given that I'm a technological troglodite (and Luddite) that's hardly a surprise.
So, say I buy an Android-based smart phone from AT&T, so it has this Carrier IQ built into its operating system. Further suppose I'd like to dump the 400 megs of OEM bloatware and try this nifty, sleeker, kinder, gentler CyanogenMod OS. How does an end user just DUMP the operating system of a smart phone and install something entirely new -- and still have a functioning smart phone that works on said user's account and telephone number?