Here's a direct link to the PDF I have with pictures:
http://home.comcast.net/~em-engineering/T2T013.pdf
From what it looks like in the pictures, apparently the buildup is just in the port, so you should be able to get some kind of tool like a dental pick in there to clean it out.
They don't seem to require removing the manifold if you grease up the drill bit and tap to catch any metal bits. However, if you did remove the manifold, you could be a little more cavalier, both with the drill and with whatever chemicals you wanted to use to try to help clean it up.