How do I change E motor microstepping from 1/16 to 1/8?

[Artesian]

I've peeked into the firmware and it's clearly quite easy to change microstepping for XYZ axes... but that's not what I want to do.

I am going to attempt to mount one of Mutley's custom "Flexstruders" with a flexible drive shaft to the effector platform. This will enable "Direct drive" printing on the Rostock. Pretty cool right?

Only problem is that his mod requires 1/8th microstepping on the E axis... and as far as I can tell there is no way to do that in firmware. Anyone know how to do this?


Thanks.