That is the problem that I'm interested.
I pump with my lo feeding in a 'rugby/football hold' (under arm) usually with a pillow under them one side and then can pump the other side.
As I only pump at night when I know lo will do a single sided feed this works best for us.
It took me AGES to figure this out tho... Tried pumping with baby in cross cradle as I didn't think of this... Doh!