Clever things you can do with grav lifts:
- Trampolines
- Man cannons
- A river that has a current
- Tunnels that only allow you to go one way
- Ramps or parts of a race track that thrust your vehicle forward
- Cover the entire ground with a low-strength grav lift to simulate the bouncing motion of a boat on water...
- Make a zip line
The size and strength of a lift are set in the phmo. As you can see, you can also decide whether the lift affects bipeds, vehicles and/or objects.
The combined values for pulsing force and gravity determine how strong the lift is. I'm not exactly sure how these values interact. Maybe one is related to how high you can go, and the other is related to how fast you ascend to that height. In any case, you will have to adjust both of them until you get a lift that acts the way you want.

Scroll down until you see these values. X, Y and Z scale determine the size of the lift. It has a rectangular prism shape. Set the Z position (currently at 0.35) to 0. The lift accelerates objects along its positive Z axis. If you want to move in a direction other than straight up, you will have to use the yaw, pitch and roll angles when spawning the lift. Note: If the Z scale is too small or the lift strength too weak, bipeds may fall through the lift if they are traveling down at high enough velocity.

Because the lift bloc is invisible, you will probably want to spawn some kind of object that lets you see where it is. Use I Can Has Cubes to make a mach that has the same dimensions as your lift (multiply the lift's X, Y, and Z scale by two for the desired mach size). Position it where you want the lift in the BSP Viewer, and then copy those coordinates for your lift bloc. If your lift is long or tall and bipeds need to travel through it, null the collision and phmo of the mach.
(If your map does not have a mach reflexive but you still want a visual model for your lift, then follow the phmo stretching tutorial using the crate_packing bloc from Zanzibar.)
Have fun.
Credits:
neodos for phmo research