Unfortunately, there are several manuals out there that say either that, or
unsigned char StandbyMode[] = {"$PMTK161,0*28\x0D\x0A"};
But yes, this is the only command.
I did just realize that I did not put it in a char array when I tried the second version I found which contained the carriage return/line feed in hex. I'm not as familiar with sending GPS module commands, but is that the standard, to send these messages this way? Regardless, I'll give that method a shot unless if you think it shouldn't matter.