Most of the time the creep range engages easily for me but if it is difficult I'll set the rpm to its minimum, the shuttle shift to neutral, and then try setting the range to creep. If it's still hard, I'll let the clutch out and in again.
my experience is that is pretty common with creeper gears. Those big gears take a while to line up, and sometimes I have to inch forward or back and work the clutch several times before it drops in.
rScotty