Apalis T30 Com3 pin mux config

I am using the WEC7 2.1b2 image with Apalis T30. By default, the transmit pin MXM pin 134 is set to GPIO instead of uart. I have tried various pin configs in the bootloader and registry, with no effect:
apalispin_19
apalispin_134
gpio_18
I am also unsure which altfn selects uart function. Altfn=1, alfn=2 or other?

The info here has been helpful, but I still can’t get it to work.

Turns out I was using image v2.0b3. I will try this again with the newer image.