[Elecraft] K3S macro to select FrontPanel (mic) or LineIn (codec)?

[Larry Gauthier (K8UT)]

For phone contesting, I would like to select the LineIn codec, transmit a
wav file, then revert to FrontPanel mic input. I have the K3S successfully
transmitting the wav audio via its codec input, but not the source switching
back-and-forth. The programmer's reference lists a command that enables both
LineIn + FrontPanel simultaneously - which is unacceptable.

The programmer's reference describes the use of MP and MQ Menu Selections
(i.e. MN053) and then refer to using " UP / DN to alter the settings." I do
not know how to combine those macros for source switching. Is there a way to
make this work?

Thanks in advance for any advice,

-larry (K8UT)