Download links are below for full A3 printable tables showing the details of the BeagleBone multiplexer settings.
To configure the BeagleBone multiplexer under Angstrom from the command line use
echo 6 > /sys/kernel/debug/omap_mux/
Where
6 = Multiplexer Mode
gpmc_a2 = the Mode0 name of the pin you are trying to configure
Results in setting of Port 9 Pin 14 soe ehrpwm1A_mux1
Download links for Mux Lookup tables
BeagleBone-Port8-Mux-A3-Rev1.pdf
BeagleBone-Port9-Mux-A3-Rev1.pdf
You also have to set the pin-mode bits in the value. For example, for an input with no pull-up, OR the mode value with 0×28. See table 9-1 in the TRM.
Also, the debugfs “files” accept the “0x” prefix, if desired.