I've created a trail map but find I'm having to tell the MapUpload program to combine my new map with the existing map already on my 60CSx. Otherwise, the transparent map seems to replace the map that was already on the unit. Do I need to select something on the GPS unit for the two maps to display together?

Trying to combine a map with existing maps in MapUpload doesn't always work. You're much better off installing your map into Mapsource and using that to load it and the topo map onto your GPS.

Using the Inno(whatever it's called) tool to compile it? The instructions looked fairly cumbersome.

Use MapSetToolKit to install your maps into Mapsource....much easier than Inno Setup. Inno Setup is more geared to making an installation file if you wanted to share your maps with others.

My custom map video tutorial shows how to use MapSetToolKit and another handy program genTYP for customizing map objects. Video plays in Windows Media Player and has step by step text instructions to follow along with video.

Download tutorial HERE.