It's not just the software that's an issue, it's the map. 'Truck' units also require that the various large vehicle restriction information be embedded in the map data. Normal consumer unit maps do not include that information.
Yes, he'll need to contact tech support. There definitely IS a Western_Europe truck map released quarterly for the 940 Live, but I believe he'll need the firmware to go with it (I believe the correct number for the last released version was 9.702). Not sure how the charges will work on a deal like that. The original 'truck' version was sold at a higher price.