Take it from all of us here... you can do it if you choose but the tranny's not built with that in mind.
This is what I've found out dicking around with those little curious little numbers down there:
You can "downshift" to second gear for some low speed passing and then shift back into drive.
If you don't defeat the overdrive gear when doing this, your tranny (well...at least my ATX) wants to go past third and directly into O.D.
Third, it's absolutely retarded. So I quit doing it while I still have a working vehicle.
I have accidentally knocked my shifter down to first WHILE DOING 65 on the highway. (I was trying to get my twenty ounce dew out of the cup holder). DON'T TRY THIS!!! Somewhere inside the ECU, it never allowed my car to actually shift down to first. Must be some sort of safety program built in.