I absolutely haven't used phc-intel a single time before, because I only own AMD machines, so I can't really comment on your problem.
But phc-k8 usually installs a modprobe hook to automatically load the phc-k8 module instead of the powernow-k8 module. It is located in the /etc/modprobe.d/phc-k8.conf file. You could check how it works with phc-intel.
One thing is sure, the cpufrequtils package (which is automatically installed with the phc kernel) tries to load an appropriate (default) kernel module (acpi-cpufreq or powernow-k8) at boot time, so the cpufrequtils package itself doesn't know anything about PHC.
Indeed it is strange that you can't unload the acpi-cpufreq module. Maybe pasdVn can comment on this.
Sure, this would be a great idea. It is already on my todo list since I started to build -phc kernels. I know it shouldn't be too hard, but it hasn't very high priority on my todo list and I haven't got time to do it so far.
If I am going to build such packages I want them to be mostly according to the Debian and Ubuntu packaging policy. You might know that it is easy to build a deb Package for personal use, were you don't care about the packaging itself too much. But my experience showed that it definitively needs more time and effort to do the packaging well according to the policy.
Nevertheless I don't want to stop people from contributing to the community. I am sure if someone builds working packages (which are at least accepted by Launchpad) it wouldn't be much problem to publish them in the PHC PPA.
As we are all working in our free time on this project, I think mostly for the personal benefit. Nobody is always available and releases are a bit sporadic. If someone thinks he can help us out with something we are currently missing, the whole community would welcome it. You see it with the contributed phc-intel pack and it was similar in the beginning of my -phc kernels. I was unlucky with the available Ubuntu undervolt kernel builds, so I started to make my own and now I am part of the PHC team.
I hope nobody feels attacked, but I just wanted to say my opinion how the whole thing works here
Moreover I hope we can welcome some new people who want to share their efforts. Open Source rules