Let’s call what you have now “Walk”; its Action will be AC:Walk. Click the X to unlink it in the Action window. Now “Add New” and call it “Sneek” (AC:Sneek). If you look in the IPO and Action windows now they will be empty.
So now you use the same rig (rig includes the Path and the Stride Bone) and pose and Keyframe it to do all the things you want it to do while sneeking (actually spelled sneaking); hold the arms out to balance; take longer steps (Loc-Y on the Char-Bone); keep his feet lower to the ground (Loc-Y on the Stride-Bone), etc…
This adds a new set of IPO’s and Keyframes to the AC:Sneek. It doesn’t affect anything in AC:Walk. If you select AC:Walk in the Action window you will see that all the IPO’s and Keyframes are still exactly as you set them originally.
Now you can do the same for Run, Limp, Look Shifty, Stumble, making each one a seperate Action.
Once you have them all done you goto the NLA window and create a Strip for each, change the icon from Action to Strip, drag them to the frames you want them to start at, Hit N and set the Blend-In and Blend-Out times and anything else you want to set in that tab.