I don't think you can? ...but I suspect this would just be a convenience rather that something that would save processing power.
Here's what I mean (relative mode only?):
Say I have an object with a 5x2 mesh (2 rows) and want to move all the top mesh points (row 0) exactly the same distance. I think currently you have to do it by changing the position values one by one (with separate events or through a loop); i.e. one event for mesh point 0,0; one for 1,0 etc, up to 4,0: So, 5 actions.
What could be convenient (to me) would be to allow more than one number in the mesh point fields (e.g. column: 0,1,2,3,4; row:0). It's rather specific, so it's only really if it would help with performance it might be worth looking at, since there's an easy workaround.