Assume you can thread a bolt into it or a sling stud, then you can use a Harris or similar that attach to the sling studs.
If you have 2 you can fit a rail to them if the spacing is adequate, like a Atlas or Seekins SRS.
Or make a extra attachment point for the rail in the stock.
You can find adaptors from picatinny to sling stud.
But if you have a rail no reason not to attach the bipod to it?
Using rails gives you more options.
Triadtactical have most of what you can be looking for, if not use some Google wizardry.
The harris with the included sling stud works very well.
My preferred method is a SRS rail with the intergrated sling stud, or a Atlas rail with integrated flush cup though.
I prefer Atlas and LRA bipods though