Using an old tutorial on a new version of Blender . Need help with 'k' key

I am following a tutorial for Blender 2.3 but using 2.5.

The tutorial refers to using the k-key.It says the k-key will toggle the Key mode in 3D view. I cant see the way to do this in 2.5. Any clues ?

I have an object moving around to 4 different locations and want to see where these locations are in the 3D view. The tutorial shows little circles that appear and say what frame number they belong to.

Im trying to work out how to see these markers in 3D view

TIA

This does not currently exist in the 2.5 series.

though this script does something simelar… http://sites.google.com/site/bartiuscrouch/scripts/motion_trail