Hi Michael,
I had been facing a similar problem on my RedHat 6.1 system. But, finally I am through with it.
After spending time figuring out what the problem was, I found that with IMAP 4.7 devel. libraries, it requires kerberos, which I am not sure is there on your RH6.2 system. But try to compile PHP with a lower version of IMAP-devel libraries(I tried IMAP4.1). Its really an old version, and even I want to use the latest but to start with your work, you can use this library.
Check for my mail. I will give you other details there.
Bhavin.