I haven't tested this yet, but it's something I've looked into before, and this looks like the most complete solution:
https://superuser.com/questions/444726/windows-how-to-add-batch-script-action-to-right-click-menu
I haven't tested this yet, but it's something I've looked into before, and this looks like the most complete solution:
https://superuser.com/questions/444726/windows-how-to-add-batch-script-action-to-right-click-menu
update: There's errors in the above answer, but it's a starting point - I got it working now