Are you looking for a full seal or just something to help hold it in place?
When I re-roofed our little storage shed I needed to tack it in place to stop it sliding around, I just used spray carpet adhesive which I always have on hand anyway, worked a treat. I also put some clear silicone under the overlap joint before nailing it since the wind got under the old one and pushed water under the lap, it's almost a flat pitch.
Roof still looks brand new 3 years later and not a bit of water has got under it not has the felt bubbled up or lifted anywhere even after severe storms.