Need neutral out at my well house but only have 220 v
I think the question is what can I do without running a new line? 

My question is do you have a grounding wire with the 220V? Because if you don't you are going to have to ground that circuit also.

Other than that you could set a small panel, split your circuits and add a buck transformer to provide you with 120V from your 220V feeder, and your going to have to ground one secondary side of the line. If you are using an autotransformer configuration the ground should be on the isolated phase of the secondary.

If all of this is a little much experience wise, I would recommend you contact a licensed electrician.

Good luck.