I have found a flat that is nearly perfect for me with only a few exceptions. One being that there is no cable or DSL service. (The owner and the Swisscom website say that DSL should be available in March (caveat emptor, of course))

While I wait for DSL, the owner says that I can use dial up. I have searched through the forums to no avail. Is anybody here on dial up? What dial up providers are available? What sort of costs will I incur?

Looking at the Swisscom website, it appears that an analog phone line costs 23.35chf/month. It also appears that it includes unlimited* calling to Swiss land lines from 7pm-7am weekdays and all weekend.

Besides the cost of the phone line, calls, and whatever the ISP charges, am I missing anything? When/If DSL becomes available will I have to pay another setup fee to get it?

*unlimited up to 300 calls/month (is there a limit on the duration?)

I would go for a USB 3G / UMTS stick solution, from Sunrise, Orange, Aldi etc. - if it is for 2 months until DSL is available, perhaps the USB on a prepaid basis.

I've already got a modem, and I can live with dial up at home for a few months. I'd rather just do that if its not prohibitively expensive or something. I am aware of the cellular Internet options.

Usually but not always, when one can have a dial up copper line, one can also get DSL services. Get confirmation from Swisscom Bluewin directly if you can.

ISDN might be available as well.

Plugging the address into the Swisscom website tells me that DSL is coming in March. You are correct, ISDN is currently available, at 43.20CHF/month. But I'd still need an ISP on the other end and an ISDN modem.

I would also go for one of the mobile solutions, but the old Sunrise dial-up still appears to be there:
Dial-up
Numéro de téléphone: 0840 555 555
Numéro de téléphone de l’étrange: +41 44 555 00 65
Nom d‘utilisateur: Sunrise
Mot de passe: freesurf
Nom de serveur / DNS
Les serveurs DNS sont normalement attribués automatiquement. Si cela ne devait pas être le cas chez vous, vous pouvez configurer manuellement les serveurs DNS avec l’adresse IP suivante:
194.230.1.39
194.230.1.71
194.230.1.103

But this will be much slower than the mobile solutions. By the way, depending on your fixed line subscription, calling the "international number" (after having removed the international prefixes) may come up much cheaper, as it should count as a national call and be included in your subscription, rather than the 0840 number which is always charged.