Can I create a boot disk for 10.6 or 10.7 on a PC (to be used on a Mac?)
Is it humanly possible, if you received an ISO from some source, that you could create a burnable disc from a PC? Yes, no reason why not.
That being said, if you have upgraded the firmware on a recent-enough MacBook Pro, and have a fast enough connection to pull down a OS install disc, you could use internet recovery:

Apple's Knowledge Base Article for Internet Recovery-Capable Macs

I believe this won't work if you hadn't run this updater on your Mac after already upgrading to Lion, but it would pull down a recovery partition of less than a GB first, from which you could at least browse the web with the 'get help online' Safari Kiosk mode, or go on to do a full reinstall.

Beyond the 10.6 disc, there is also a USB drive for Lion that can be purchased as well, of course. Good luck