I just programmed MRLcomm version 35 into my Arduino Mega 2560 and am trying to communicate with it from a Windows C++ program I wrote. I can find the Mega, open the COM port, and get the MRLcomm version and acknowledgement successfully. I can also attach a servo to a pin, after which the servo centers.
However, if I try to use the writeMicroseconds() function via MRLcomm the servo pulse always goes to the minimum (544uS). In the MRLcomm code only a single byte (ioCmd) is being passed to the Arduino Servo Library function. Since a byte cannot represent the necessary 1000 to 2000 uS range it appears the Arduino library defaults to the minimum value. It seems MRLcomm needs to build an integer from 2 bytes and pass that. Of course, this brings up the Big-endian vs. Little-endian question, but either should be fine as long as it is documented.