http://rmxp.org/forums/index.php?topic=10194.0
Honestly that's not exactly what your looking for. It's a tut with lots of set images for you to place on a "map" using photoshop, and has some info and such for you to read and learn some from.
Your best bet is going to the tutorial section and looking around.
Want to search? Good, go to the tutorial section. There's a search box on every page of the forum in the upper right hand corner. Put in "Photoshop" and that little drop down next to it (where it says "Entire Forum" by default) move that to "this board", and click search.
I would suggest looking at every photoshop tutorial, they may not all be useful for you - but even those not drawn up for mapping in this style could certainly be of use for you.
However this is not a resource analysis thread, and I suggest all future lookups for tutorials be made with the search feature, there is a thread intended for any and all tutorials one might be requesting (
http://rmxp.org/forums/index.php?topic=21912.0) in the tutorial section.
This thread is closed.
Have a good day, don't be afraid to ask questions in the proper tutorial section.
EDIT:
BTW the thread I linked to at the top of my post is the EXACT same one Ryanna linked too ... oops :x