Doesn't seem too hard in principle...
Each joint has a maximum of 2 angular values associated with its configuration- I count about 14 important joints used in walking (wrists,elbows,shoulders,neck; torso, upper legs-pelvis, knees, ankles). The walking motion should be roughly captured in a time-evolution of these ~28 parameters. Assuming each one is sinusoidal (and therefore has 3 parameters: amplitude, frequency and relative phase) you will have 28*3 - 1 total parameters if you define eg. the neck to be phase 0.
The hard part I guess would be illustrating that your results are correct since a bunch of numbers is hard to compare to the actual walking motion! I guess you will just study a human walk and a few simple measurements should give you the answers.