Install ClockWorkMod
Downloaded a recovery.tar.md5 from http://droidbasement.com/db-blog/?p=2668
http://droidbasement.com/galaxy/recovery/cwm5/p4wifi/5/recovery.tar.md5
Boot to download mode (power + vol down)
Start odin3_v3.04(Samsung flash tool)
found it here http://androidlegend.com/update-samsung-galaxy-tab-10-1-wi-fi-p7510-with-ics-4-0-4-uelpl , odin http://www.androidlegend.com/dl/odin3_v3.04.zip
When odin reports connection, add the revovery.tar.md5 to the PDA field
Press start and you should hopefully be ok.
Install CyanogenMod according to http://wiki.cyanogenmod.com/wiki/Samsung_Galaxy_Tab_10.1_(Wi-Fi):_Full_Update_Guide . Note the previous part about ClockWorkMod worked for me. The wiki has another version.
Method via Recovery


Download the latest version of CyanogenMod.
Optional: Download the Google Apps for the device.
Place the CyanogenMod update.zip file on the root of the SD card.
Optional: Place the Google Apps .zip on the root of the SD card also.
Boot into the ClockworkMod Recovery.
Once the device boots into the ClockworkMod Recovery, use the side volume buttons to move around, and either the power button or the trackball to select.
Optional: Select backup and restore to create a backup of current installation on the Samsung Galaxy Tab 10.1 (Wi-Fi).
Select the option to Wipe data/factory reset.
Then select the option to Wipe cache partition.
Select Install zip from sdcard.
Select Choose zip from sdcard.
Select the CyanogenMod update.zip.
Optional: Install the Google Apps by performing steps 7 - 9 again and choosing the Google Apps update.zip.
Once the installation has finished, select +++++Go Back+++++ to get back to the main menu, and select the Reboot system now option. The Samsung Galaxy Tab 10.1 (Wi-Fi) should now boot into CyanogenMod.

Method via ROM Manager

Launch RomManager.
Optional: Choose the first option in the app, Flash ClockworkMod Recovery to update to the latest version.
Select the Download ROM option from the main menu in the ROM Manager.
Select the CyanogenMod option, and then choose the latest version of CyanogenMod from the menu.
Optional: When you select the latest version of CyanogenMod, check the Google Apps option.
Once the ROM is finished downloading, it asks if you would like to Backup Existing ROM and Wipe Data and Cache.
If Superuser prompts for root permissions check to Remember and then Allow.
The Samsung Galaxy Tab 10.1 (Wi-Fi) will now reboot into the recovery, wipe data and cache, and then install CyanogenMod. When it's finished installing it will reboot into CyanogenMod.