If you need to combine the maps from here with those from malsing or elsewhere.
As of v3.70, SGJoh Road Name map is no longer in the gmapsupp.
Method A
Copy my gmapsupp.img and gmapsupp.unl into the Garmin folder of the device and malsing's gmapsupp.img into the SD card.
Method B - use SendMap2.0. (Note: House number and Street name search will not work if you combine maps with SendMap)
1. Download my SG-R & JOH-R MapSource Installer or GMAPSUPP vx.xx and malsing's GM-MySin MapSource Installer.
2. Run/Extract the installer/zip file and remember the location.
3. Open SendMap and use Add Maps button to add the maps you want from malsing (except malsing's 60000077.img and 60000078.img). Next, follow either a. or b. below depending on your GPS model.
a. Nuvi, StreetPilots or Mobile XT users:
Use Add Maps button to add my extracted GMAPSUPP.IMG and your list should look like the diagram below 
b. Garmin hand-held models:
Use Add Maps button to add my 60000077.img, 60000078.img and SGJOHMAP.TYP, your list should look like the diagram below 
3. You'll need to add 3 unlock codes one at a time (2 for malsingmaps and 1 for my map). Click the Add unlock key button to add the first unlock code. Click the Add unlock key button again to add the second unlock code, repeat this process for the third unlock code and so on.
4. Click either Upload maps to GPS (depending on whether your GPS is supported) or Create GMAPSUPP.IMG button and select a different location from where you extracted my GMAPSUPP>IMG (after which, copy the GMAPSUPP.IMG to the Garmin folder on your GPS)