I have had the same issues with windows 7 and M4 software. I have been able to get dosbox to run the software exactly as your advice. However, I am having difficulty with coms. I am using an ATEN serial to USB configured with the UC232A driver as COM1. I have entered the following under serial in the dosbox options config file:
serial1=directserial realport:com1 rxdelay:1
When connecting to the ECU, the communcations are established (the ecu serial number and options row populates on the menu screen), then immediately drop out. Changing the rxdelay appears to have some effect on the time to drop out, but no value I have tried has stayed connected long enough to actually open a map.
Any help would be greatly appreciated.