in this model of laptop the dvd rom is one of those slot loaders and there is no external part of it visible, he is going to have to dismantle the whole case to get to it.
Ya, I realize that now. I for some reason thought he was talking about a Latitude.
First off... Google the model number and "dell" and "disassembly guide" together.
9 out of 10 times there's a site with a pictorial guide out there.
If that fails, go ask at the Notebookreview.com forums. Someone's probably modded
the tar out of one already and could tell you how to assemble it upside down and blindfolded.
This is you best bet. To state what is (hopefully) obvious, even if you can't find the exact disassembly guide for your model, disassembly guides for related designs will prove useful for figuring out how to take it apart. If you do manage to start taking it apart without an explicit disassembly guide make sure that you take pictures of the stages so that you know how to put it back together

I seem to recall that Dell used to have a reputation for sealing their old laptops shut to prevent upgrades, and therefore sell more computers. I think there was a bit of a storm about it a few years ago? Didn't they also used to use non-standard power connectors for the same reason?
Yep, and certain models still do. Though pretty much every laptop builder has slightly different power connectors, they luckily keep them mostly the same across multiple model lines.