Cyanogenmod has made OFFICIAL Nightly builds for the HP Touchpad.
This video will explain how to install them.
Download the latest Nightly build from here:
And the gapps file from 3/17 from here:
Copy these files to your Touchpad, then use Clockwork Recovery to install the zip files. Clear your cache and Dalvik cache, and reboot.
This nightly has ICS 4.0.4 built into it, along with some other nice improvements, including a NEW WIFI DRIVER!
Post in the forums, and read the articles for assistance.