Been Googling and looking at code for a couple of hours. I've seen a few javascript implementations but honestly I haven't the slightest idea how to port it over. The whole thing's above my head. I'd like to have this in PHP. Can anyone help?
Here's a tiny python implementation that should be much easier to port to PHP:
https://github.com/bkkcoins/misc/blob/master/hexwif/hexwif