I think Greg is trying to configure his computer to accept dialup calls from the phone network so that he can, in effect, be his own ISP, relaying the connection out his existing cable modem.
If reading the PPP howto is too complicated, consider Slirp:
http://slirp.sourceforge.net/
I used slirp on Linux starting around 1995 to provide myself with mobile dialup access to my work computer as well as Internet access. I haven't used it in years, but I recall it as being very easy to compile and install.