Leisure Suit Larry: Box Office Bust

This is the best and easiest way.

Go to the theater then go to the left where you see the man and the soda machine.

You'll see three sills holding plants to the right of the machine. Grabbed any of the overhangs and climb to the right or left until you hit the wall. Then jump three times against the wall. you'll land on the same overhang everytime and the achievement will unlock.

This is easy to do and can be achieved at any time. All you have to do it jump from 1 ledge to another, then back, then back again. 3 total jumps. You have to be hanging from your hands and land/catch with your hands.

Theater - Enter the theater and go to the far left. Jump up on the soda machine and grab the overhang. Then just jump to the next ledge, back to the original, then back again.

Western - During the initial train ride when you have to climb over some hay bails. There is an area where you can jump between bails of hay.

Western - During the climb down to the Prospector. There are several ledges that are good for this achievement.

Bytanic - During the Bytanic climb there are several ledges to perform these jumps.

To clarify, this has to be the "side to side" ledge jumps where larry shifts his body to prepare for the sideways jump. You cant just do up and down jumps between ledges. I found the Bytanic climb was a very easy place to do this, although I didnt bother trying the other places recommended above.