This little video popped up on youtube a few hours ago.
Which can be seen here.
[ame=http://uk.youtube.com/watch?v=OD2jk2IOtu4&feature=channel_page]YouTube - OotHE - Deadmines Redone[/ame]
I take no credit for this video nor this method, however I can confirm this is working.
Likely hood is this will be nerfed very shortly. Enjoy while you guys can.
And yes, you can wallwalk in deadmines, this probably has something to do with all the annoying invisable walls.