I had great fun removing my rocker cover too...
When a coil pack on the rear bank started misfiring from oil leaking into the spark plug wells, had no choice but to replace my rear rocker cover gasket.
It ended up taking the best part of a day and most of that time was spent removing the old gasket.
I tried all the scrapers, blades and chisels I had to remove it without damaging the rocker cover or my hands. In the end I used a grout removing blade
on the end of a reciprocating saw to chew out the bulk of the gasket, inch by inch, leaving the last mm in the base of the channel to scrape out with a chisel.
To be sure that it wasn't going to leak, a smear of silicone applied the channel before dropping in the gasket took care of the sealing as there were still traces of gasket stuck in the cover channel.
While it was a success, it put me off doing the front bank until it leaked.
Now two years later the front one one has begun to leak...
A number of mechanics have told me - if it's a 380 - there is no easy way...it depends on luck how bad it is.
If anyone has any magic chemical or technique - I'd appreciate knowing about it!