You don't.
No new term is needed, 'woman' is just fine. I note one of their examples( 'womxn' in physics shows a stand with labels 'women in physics', as it should.
'Women' includes all women, and the fact that it includes the syllable 'men' is irrelevant (especially if you consider the etymology - 'man' used to be neutral, blokes were wermen).
The only problem at the moment with 'women' is that some people want it to include people who aren't women. Exactly the same would doubtless apply to 'womxn'.
It's a non-solution to the wrong problem.