As a variation on what jolly logger said, something that has worked for me is similar, but with a 2:1. Instead of running the rope from your winch, up the tree, than down to the log, tie one end of the rope to the top of the tree, take the rope down the hill to the log, attach a block to the log, then take the rope back up the hill to your winch. You get a little less lift this way, but you double your pulling capacity. If you don't have the winch, you can use the skidder as the pull, set a pulley in the same tree high enough off the ground that the rope won't snag, then pull with the mini. Setting the 'pull end' of the rope closer to the ground means that you get more pull too. If you were trying to pull from the higher pulley, the angle of the rope would be trying to lift the mini off the ground as you were pulling, reducing your traction.
Shaun