I had the same problem except that I was using hot glue in the middle of winter. I would put the glue down and it would harden before the 2x2 ever touched it.
So I clamped the pieces down, drilled, and screwed. After you drill, you can go back and add glue before you screw them in for added support. If your clamps do not have the reach to properly hold the piece in place you will have to rig something up. I ended up clamping a piece of wood on each side and then clamped them to the piece I was setting. Hard to describe, but it worked.