I'm in the same boat here pulsery2k1.
If I run into a place that won't deliver to PO boxes I put the physical address of the local Post Office as my mailing address and then add my PO Box number to the zipcode. For example, if my zipcode it 77777 and my PO Box is 1234 then I would change my delivery zipcode to 77777-1234. I've even made up addresses like 101 Main Street as long as my zipcode could be amended to reflect my PO Box.
Try this at your own risk! I live in a small town and the folks at the Post Office know me by name. A letter would still get delivered to me if it only had my name and the zipcode on it!
I certainly wouldn't do this with a high dollar part for my first attempt. Try sending yourself a letter and see if it makes it.