Put this in the group leader's init field:
{_x allowfleeing 0} foreach units group this;
Also, set the speed mode of the group to FULL in the waypoint.
You may also want to set the unit position of the units to "UP", this will mean they won't get down and crawl all the way. Put the following code in the group leader's init field to make the soldiers stand up:
{_x setunitpos "UP"} foreach units group this;
-Pilot