BC fan here. I echo the Riverside suggestion. Easy access from the Pike and 128. Take the D line from there and get off at Chestnut Hill and walk down Hammond Street to campus. Don't try driving to campus to park unless you pay for the Lower Brighton pass (needs to be ordered beforehand). The Hammond Pond Parkway suggestion someone made above also isn't bad. I used to park there approximately 10 years ago, so I can't say whether it's still allowed now, but it's an easy walk up Beacon to campus from there.
For the UConn fans without a spot to tailgate on campus, I'd suggest bringing a cooler with beers and setting yourself up somewhere on lower campus. Somewhere like the mod lot might be a good spot for that. Another option a little further from the stadium but with a livelier scene (especially for people in their 20s) is the Upper Brighton lot area on the Brighton Campus. Drinking is allowed anywhere on campus during the tailgating hours (3hrs before and 2 hrs after the game), so it's just a matter of finding a place to plop yourself down. It's not ideal (we don't have a lot of space), but we make the best of it and it can still be a really good time.
For an idea of the areas I'm describing, check out the PDF map linked below. Note that what I (and everyone else at BC) call the mod lot is referred to as "Robsham Theater" on the map.
https://www.bc.edu/content/dam/files/top/alumni/pdf/BC_GOLD_Parking_Map2106.pdf