I want to place a switch between a 1.5V battery and a small tweeter on a clock. Does it matter if I place the switch between the positive or the negative lead?

 

not in the least

 

A good practice is to place a switch on the positive (DC) or the hot (AC) side of any circuit. It's safer that way.

 

Are you sure the tweeter will work on 1.5v from a battery? Many of them require a signal generated by the clock and will not work on DC