nope.
Unless you want the flash hider sling adapter and rear sling plate mount, but the flashhider/outer barrel is very weak you don't want to be holding the weight of the gun on it. I've seen realsteel configs like that.
there's the rear slot where you can mount the sling adapter for a 1 point.
The vestguy has several pretty shitty options to choose from plus a stargate style adaptation, which seems to be the one that's worth anything that isn't just a bunch of 1.5" webbing with shitty plastic hardware and a few lines of stitching.
There's the actual stargate screen accurate repro sling..
http://www.stitchsloft.com/loft/scre...-p-90-harness/ that's super expensive but I think it's the best one, but it limits your 2nd line options since it's a harness that fits under a vest. So if you wear a plate carrier it sort of fucks you over.
Technically all you need is the band that wraps behind the buttstock through the back of the thumbhole with some hardware and you can use any 1 point you want and it rests higher than using the adapter plate at the back/bottom. You can make that with 1" webbing, a buckle and 2 triglides. Then stitch in a loop in the webbing that you can slip a loop of some sort through to hook a 1 point on. It's not too much stitching you could do it by hand, it'll be a bitch though. That's about 10 bucks worth of stuff. You could also take it to a tailor or alterations place and have them run the stitch for you on an industrial machine.
If you have a tri rail config you can rail mount a magpul rsa or any other rail mount sling loop as well with the rear mount to give you 2 point options.
Those are your only options for p90 slinging. Expensive Stargate style or buy the expensive mounts and use an existing 1 or 2 point.