I dealt with one of those a little while back. I would have swapped with the screw-type, but the lower rad hose-to-radiator joint is "recessed" in such a way (at least on the '04 LeSabre) that I wouldn't be able to get a screwdriver in there anyway...had to attack it sideways with pliers.
Like these guys have said, if you plier that thing wide enough, it will "lock" open. Then once put back into place, hit it with the pliers again and it will snap shut.
When locked open, it'* like a hair-trigger rat rap, so be careful!
2004 Buick Lesabre Limited, Gran Touring; Bone Stock
1998 Buick Lesabre Limited, Gran Touring; Mods: Poly sway bushings/endlinks, Tru-Cool trans cooler, Thrasher shift kit (med), PLIM, front PEM; Mods in progress: Alot of stuff, but slowly...