I did this in my lab by following the instructions:
1. Shut UIM down. (UMP and All Hubs)
2. Apply MySQL RPM update to 5.5
3. Statrt UIM
When I was done the DB was rendered "corrupt" and the data_engine would not connect due to "courrpt" tables.
I didn't massage any tables post-MySQL upgrade. Should I have?
Thanks
-Rob