maybe this will help. (i started the thread asking for the DoDesolation conversion). i found it ... in a manner of speaking, and you can use it to run the supermodule for your group under 3.5E rules ... though it appears to be a
3E conversion (not 3.5). it should be easy enough to still run it however, either without full attacks from the baddies or just convert the monster stats yourself.
go to google.
search for "desertofdesolation.pdf"
the second result is the pdf file, but the link is dead
click on "view as HTML"
go to file menu and save the HTML page onto your hard drive
apparently google has it archived in HTML format for the moment.
though it's not in pdf format, it's better than nothing!
happy gaming, my friend!
EDIT: i've personally never done a conversion myself, but i imagine the basic idea is as follows. if you want to keep the 5th to 7th level recommendation but for a party of four, just adjust the EL for each encounter by either decreasing the number of foes or decreasing the CR/HD/monster so that the it will provide a similar relative challenge for the players.
or you could increase the recommended level to something like 8th-10th for four players, and keep the EL about the same.
just a guess. i played AD&D for years and years, but have only been playing 3.5E for a few months, so i'm not an expert by any means here.
good luck, and if you find out any sage conversion advice, please feel free to share it with me!