loop control with 4-mx and vdj7 le

hi,
do you know if it is possible to shift the loop-in point with hercules 4mx and vdj 7le? i know i can increase/ decrese the number of beats in the loop but till now i was not able to shift the loop position...

Having  similar problem with V-DJ Pro, I seem to be able to Loop In and Loop Out / set the number of beats in a loop etc.
But once the beat is looped in the Loop - in Button doesn't seem to want to shift to the point pressed.
It just restarts at the start of the loop when originally pressed!