As long as you have a true 5 pin MIDI out connection from your PC or audio interface to the MU100, you should be fine. There is even an Instrument Definition file available for the MU100 so all the MU100 patch names and drum maps appear correctly in Sonar.
Note: I have a similar set up but instead of the MU100, I have an external SFF PC with a Yamaha SW1000XG installed (Basically a PCI version of the MU100) being driven by a USB to MIDI converter. I use this with Cakewalk Pro Audio 9 and with Sonar Platinum (early release 2017)