You might want to double check the town the Bodega Torres is in. I believe it is outside of Vilafranca del Penedés, which is northwest of Sitges...and I know this because I took the wrong train and accidentaly got to see the exterior of Torres winery first hand from the train...at night...going the wrong direction. Had I know that was where I was going, I would have requested a tour

Seriously, the regionales can be a bit confusing when leaving from Sants in Barcelona (if that is where you are leaving from) because many (and I mean many) of them leave from the same two platforms. Not impossible, just a bit confusing. You could probably take the Regional and then catch a cab to the winery in Pacs, if you needed to, or just walk. Who knows, maybe they even have a shuttle to the winery from town.

According to Lonely Planet, the actual winery is located about 3 km northwest of town center in Pacs. Here is their web site Torres winery tour in Pacs

Have a great time!