The player will have velocities and acceleration while on ice, and will take time to gain and/or lose speed, as well as turn. This gives the feeling of the ice truly being slippery.
Two item IDs can be specified; the first will alter the slipperiness of the ice, giving you more "traction", and making it easier to maneuver- while still slipping some. The second will completely disable the ice, giving you the ability to walk on it as normal.
KNOWN ISSUES: Since you are not walking using the engine while on ice, things like pushing into the side of a lockblock to open it do not work while on ice. This likely also applies to pushblocks, making this not really work for pushblock ice puzzles, sadly.
Firstly, adjust the constants in the script file to your liking (specifying item IDs for the traction items, the combo type that will act as ice, etc)
Compile the script, assign it to a slot, and set "Run from Start" in "Init Data" for the script. You can also adjust the acceleration/deceleration values as InitD[] for the script (? buttons explain in more detail)