you could use a phone to photograph it.
Viewing post in How do you all cope with 'Freezing creatively'
Yeah, then cut out the white background, increase the contrast and cut out anything that isn't your lines. Then you've got a nice .png to work with. Sure, it's not vector art, but it works. Of course you could photograph the map and just trace vectors over it, that would be even better, but the other way works fine.