Hi Mograg! Good question! Essentially as I was building Dead Halt I was using other adventure plot lines so that I didn't always have to make up my own. The "conversion" aspect of this is simple, as Dead Halt is quite rules light what I would always do is take the story line, maps, and creatures and use those, and as creatures don't have super lengthy stats in DH I would use their main attack quirk or whatnot as their effect agains the Crew.
Dead Halt is meant to be super easy to jump into, and how I do this is I grab an adventure book, start reading at the beginning of an interesting arc or part of the adventure, and then let it fuel my ideas as my players react. The best part of this though is that it is going to be wacky no matter what. If you run the story and dungeon of Tomb of Horrors, in DH your players might have TNT and guns and other wild tech.
Its makes for some incredibly silly and really enjoyable games, as players get incredibly creative. (I have run TOH in DH by the way... It was hilarious.) Long story short, Dead Halt is very casual and open ended. You have to have an open mind and be very creative, there arn't a lot of stats, number crunching, or anything like that, but it can lead to some wonderful stories you never expected to have.
Hope this helps!