plus / minus override

i was wondering if there´s a way to do a kind of command to swap the "sign" (positive or negative, + or -) of the max commands. Like at the slide edge command on edit poly. Is always annoying when you need to change the way of the new edge and have to put a minus sign in front of the number. this kind of situation happens a lot of times, like in the array command, when ou want to copy objects to inverse direction, you need to select the box and put the sign in front of the number again. in a script with a shortcut key it will be very much easier and quicker, but i really don´t know if it´s possible to do with maxscript.
Anyway, that´s my suggestion for a useful script(in my opinion ;).
thanks for your attention,

jsrocha - Brasil