In general, I don't recall Volvo using much in the way of adhesives to hold the door or tailgate opening rubber gaskets in place, also the trunk seal. Having said that, with used rubber I would be tempted to tack them down in a few places just to make sure, like a small blob every 8" or so, especially at the corners. Just don't use a blob that would make a lump in the gasket. I have in the past used plumber's caulk behind the rubber to raise the gasket a bit after pulling a strip of newspaper to reveal less that a tight fit in that spot. A number of flexible adhesives would likely work well, including RTV, but not so much silicone-type sealants, rather something with a bit more tack, also rated for rubber. What I would probably do is start by installing them dry and as you go, if it seems like they could easily be pulled out, then go for the adhesives.