As far as I know Jamstudio can't split a measure.one way you can do that is with editing equipment and jamstudio Loops
http://www.jloops.com/index.htm By useing jamstudio Loops you can make the same song with editing equipment you can then take the time line and make the beat 1/4 1/2 3/4/ 4/4 beats / measure. I can take my equipment to 1/16 triplet notes.