You can find most of the tools here:

http://www.atomicgamer.com/directory.php?id=1173

And this bit wasn't a joke: 'Seriously, put aside about two months where you expect to do nothing else with your spare time.'

As with all things it's best to start small and build up as you crack each level.

Quote Originally Posted by Caravel
Mithel is the key to the problem as without it, it's a massive struggle.
I cannot stress enough that Mithel is THE KEY to mapmaking - and it is available from the link above.

It also has LMM up there for when you're ready to do a complete new map - however, to use it you will also need to download a DLL from here. This is a free trial version, but you can keep downloading new copies each month, don't worry about having to finish your map in 30 days etc.

I don't think there is a complete step-by-step guide, just lots of useful bits of information scattered around the Org and the "readme" files of the tools. Really, the LMM thread is the closest you'll get, but even that will assume you already know most of it.