TLH would take I figure a number of hours to do right. Yeah you can remove some of the superfolous things like the Poison Ivy subplot, the Bruce Wayne trial, truncate the Joker subplot, etc. But the meat is still there with the Holiday killers, the mafia's role, the early issues of it coming out, Maroni going on trial, Dent's scarring, the son being the culprit, the rise of Two-Face, etc.
All pretty great stuff. Maybe take out the villain-of-the-issue aspect and leave only Two-Face, Solomn Grundy, Catwoman, the Joker and the mob. Also, have some of the detective work occur on non-holidays as it seems Dent and Gordon would get a lead and then sit on it for am month or two right until the next holiday murder is about to be committed.
Oh well.