Lost_luggage34 is quite correct..
Macs connect to the internet in exactly the same way as other computers. All new macs come with internal 56k v.92 modems as standard.
So, she will be able to connect anywhere in the house where she is able to reach a phone point, which will involve either the standard modem lead direct into the phone socket, or via an extension (I have a brand-new 15m one on a nice, tidy wind-in reel for sale, PM me if you're interested)
But, with broadband access now available for just a few pounds per month more than dialup, why doesn't she just take the plunge and get connected to the fast lane? I've just done it, and believe me it's well worth the slightly higher price.
Jx
P.S - I can also happily recommend my ISP,
Zen - not the cheapest, but customer service and speeds are excellent.