If you're having trouble creating the TMC file with the right co-ordinates, or finding that after your geoconvert run you have no scenery files, try this. It takes the co-ordinate data directly from FSET and makes a TMC file from it.
It's had a few updates and improvements since my weekend post. Thanks to everyone who's helped me debug the earlier problems with this.
Also, if you're interested, here's a zip file of FSET pre-configured with the latest INI file and all the checkbox settings which the wiki recommends for generating output for FS2.