I have a folder on my pc called custom poi, I add points in Mapsource & then save each map as a gpx file.
So far I use 5 files, "added map poi, benchmarks, home poi, other poi & Waymarking poi".
I use Easygps ( lets me select an icon for each custom poi ) to load the files into my 60Cx ( using Mapsource to load gave me blue dots for icons ).
To locate a custom poi, select find, then custom poi, there now is a list of the poi. Pushing menu lets me select my custom poi by database (same as my file names) or nearest.
I add or delete custom poi by loading the particular file into Mapsource, make changes, save & send the file to my gps via Easygps.