I have gotten 10.8.2 running on the Dell Latitude E5520. I don't remember all of the steps I took to get it running because I worked on it between classes (I am a teacher) and did a little at a time over a weeklong period. I used the unifail+multifail method that I found outlined here. I don't have a DSDT, and I'm still a n00b at all this, so I don't know how to create or patch a DSDT or whatever it is you do with that. I know that to boot I have to have -v and cpus=1 as arguments, or I get KP. I also had to put in an Atheros wifi card (I don't remember the model, but it came out of an EEEPC 1005HAB and I knew it worked in OSX on that netbook), but since there are two card slots, I moved the Dell card to the other slot and put the Atheros card where the original one was. I'm not sure if the second slot was for a second wifi card, or if it was for a cellular card, but my wifi is working just fine. I haven't gotten the sound working correctly yet, either. I tried VoodooHDA 2.7.3 (I think), and it appeared to work at first, but the volume was always maxed out, even if I had it muted. I haven't tried anything else to fix that. I also haven't tried hooking it up to the projector in my room to see if it will mirror/extend the display, but I hope to do that soon. As a teacher with students who use both PCs and Macs, it would be nice to be able to let them present using the same software with which they completed assignments.
Hope this helps, at least some.