Haven't anyone tried this yet? I believe that the map in navigation will fit any resolution, even HD but maybe the menu interface will be a bit smaller since the resolution is 520x234. However, the navigation map will stretch automatically, maybe a bit less sharp in HD. It can use the R12 map found [Please Register or Login to download file]
, which is from MK SG with a change to Hex address 00000020h from E5 A8 E9 A8 FB A8 E1 ... to E5 A8 9B A8 F0 A8 91 A8 F7 A8 E5 A8 E5 A8 E9 A8. The map latest update currently is Nov 2010 for MY and SG, which is not bad. The POI icons are not customised e.g. McD icons, etc. but it will get you somewhere accurately considering how current the map is (I've tried it in another MK version).
The only problem is that there is currently no Happy File for other COM ports, except the original, which I presume is COM2. So, if Tony or other sifus could help to identify which address to change the COM ports, that would be amazing. Till then, it cannot be tested on GPS with other COM ports