Do I have to do anything different to TI’s Pin-Mux utility to work with the OSD335x?

No, you don’t. The AM335x die in the OSD335x is the same as the Die in the discrete TI device.  This means that the Pin Mux will work the same on the OSD335x as it would on the discrete version. There are minor differences in location and position of a few signals. Please refer to question ‘What are the differences in ball maps of AM335x and OSD335x?‘ for ball map differences between OSD335x and AM335x.