Are you using linux or Windows?
I bought the necessary cable from radio shack, just the cable not the software, it was around $20-$25. Friend of mine sent me the Windows drivers for it if you need them. When I was testing out my EPIA a few months back I had PPP access working under linux too, I believe the necessary drivers are built-in. Unfortunately its been a while so I don't remember exactly. If you got windows, then its easy.