I've got an inexpensive Nashbar frame pump on mine. The LHT frame has a little stud on the back of the head tube that mates up perfectly with a little hole in one end of the pump. The angle between the top tube and the head tube is greater than 90 degrees, so without the stud the end of the pump would slip out. The other end of the pump fits up into the angle between the top tube and the seat tube, which is less than 90 degrees, so it stays wedged up into the angle. The pump itself is spring loaded so that the two ends are pushed apart by the spring, thereby holding the pump into position.

Be careful to buy a pump that is the correct length for the space it's going to fit in - for my LHT (60cm frame) the largest one is perfect.

The pump stays in position perfectly, and I have no trouble pumping my 700 x 28's up to 105 lbs with it.