actually, i think it shouldn't be:

we walk with you, every step of the way, from the initial conceptual design, through case illustration, document drafting, and implementation.

nor

we walk with you every step of the way, from initial conceptual design, through case illustration, document drafting, and implementation.

infact, the sentence is just too long i think, so i would actually just rephrase it...

i would write it:

from initial conceptual design, through case illustration, document drafting, and implementation, we walk with you every step of the way.

hmm, i have no clue if any of this is right, it just sounds right to me haha.

by the way, nice site ^_^