We've played it this way and it is actually really disappointing as a co-op. In the end it is more like "solitary" in that one person really "wins" it for everyone. Rarely do the players who don't make it to the middle really contribute much to the victory.
Awwwww, dang it. *ponders* hmmmm...anyone else have similar or different experiences?
A proper co-op expansion to Talisman (or Relic) would be great. Until then, I think your best bet for that kind of experience is to play the Pathfinder Adventure Card Game.
Thanks for the advice, but unfortunately we don't own the PACG. We're all on a pretty small gift budget, sadly.