I set up MythTV on CentOS 5 last year. I was surprised to find that the CentOS kernel is not compiled with dvb support. I didn't check any further, but who knows what else is missing!
I ended up downloading the kernel source from kernel.org, and compiled a new kernel myself. I used a kernel config file from a Suse install, as they have everything compiled into it.
I also installed MythTV from (SVN) source, as I don't see it available from CentOS.
Your guide really isn't about MythTV at all. I hope you do a little more research on this subject!