1) Make sure that your cable account doesn't in fact offer a dial-up account as part of the deal. Then, there may be "roaming" numbers that you can use to dial-up.
2) Get a $4.95/3 hours/month AOL account for such situations.
3) Get a Netzero free dialup account (although it'll drive you crazy with popups and the number of free access points/numbers has declined istm)