OK, I'll make a step-by-step list of instructions for updating ICS solely through the TouchPad (assuming you already have an install of ICS along with associated programs (Moboot and ClockworkMod Recovery, which you should):
1. Download the latest release from
CyanogenMod Downloads. All releases are currently nightly, but there probably will be release candidate versions soon (CM9 RC releases has appeared for other devices recently). By default, the ICS Browser saves it to the Download folder. If you use another browser or manually changed the download location, this may be different.
2. Reboot into ClockworkMod Recovery. You should be able to do this by holding down the power button until the options appear, then choosing Reboot -> Recovery.
3. Once in CWM Recovery, use the volume buttons to choose the "wipe cache partition" option and the home button to select it. Confirm by selecting "Yes - Wipe Cache".
4. Select "advanced", and then "Wipe Dalvik Cache". Confirm.
5. Go back to main menu in CWM Recovery and select "install zip from sdcard" -> "choose zip from sdcard". Then navigate to the download location in step 1 and select the ZIP file downloaded. Confirm the install.
6. Go back to main menu and choose "reboot system now". The tablet should reboot into ICS, and you should then have the latest version.
The same process is used for basically everything CM9-related you might want to install (gapps, the wi-fi driver from a couple weeks ago, etc). You just choose the proper ZIP file.
If you download the ZIP file on your computer, the process is the same, you just have to copy the ZIP onto the TouchPad and choose the appropriate file.