Instead of a syringe-type dispensation of the paste, why not build a mini-stencil with a simple solenoid to move a little squeegee? You'd need a syringe to dispense more solder paste onto the mini-stencil, of course, but it wouldn't need to be nearly as accurate as if you were dispensing the paste onto the pad with the syringe directly as the mini-stencil would keep the paste in a uniform shape and thickness.

I was just browsing threads, I don't have a lot of experience with PnP but I'm familiar.