Is it Grindelwald in Berner Oberland? You can find most train schedules at www.bahn.com. If you travel date is way in the future, use the same day of the week in Jan. The schedule does not change that much and you get at least some idea about connections. If Switzerland and Italy are the only destinations, you might want to compare your current thinking vs. Swiss specific pass such as Swisspass/Halfare card plus no pass for Italy. Why? Italian trains where a pass has some cost merit also impose reservation requirement and fees http://www.ricksteves.com/rail/pdfs/reservations.pdf, so you cannot just hop on these high speed trains. Between additional fees and reservation requirement vs. online point to point discount which always includes reservation, even these high priced Italian trains often favor point to point tickets. For slow Italian trains where you can hop on and off are so cheap it is very difficult for pass to be cost effective. Switzerland is a different matter and some kind of passes make sense for many especially if you are going up into the mountains. High mountain fares are quite high, and different passes give different coverage and discounts in these areas.

Forget passes, just buy a ticket if this is all you want to do.

The trick is to find a journey using www.bahn.de/en then split the booking.

La Spezia to Milan from €9 www.trenitalia.com

Milan to Spiez from €19 on a direct train at www.fsitaliane.it looking for smart fare when you select the train and see the more fares box.

Spiez to Grindelwald fixed price so can be bought on the day at Spiez, www.sbb.ch for prices.