Just download the 4.0 files from wherever (piratebay)...
Get a set of maps (you can use the old maps or update them).
Put the maps, POIs, DEMs, in the respective /ap2/iGo/content files...
Put all the (updated with maps) files from 4.0 download onto an sd card.
The files are: The copy file (with all the AP1, 2, 3...)
Data,zip
testmode (file)
wince (bin file)
wince (cks file)
At this point you can follow the 3.0 install sticky guide...
put in the card, start up the car... hold all four buttons... let go of the reset button, keeping your fingers on menu+map...
@ the blue sc