http://www.fpsbanana.com/games/media/view/8879
Pretty pointless, but damn it looks good.
And yes, I know how it was done, but not how to do it, if you catch my drift.

After a bit of searching, I found it!
As I suspected, it only works on servers that dont enforce consistency.
http://rs305.rapidshare.com/files/88488584/nanosuit.rar

To make your own server that has no consistency, open notepad and type

Then set filetype as all files and type .cfg as the file exension. Put this in Steam\steamapps\username\counter-strike source\cstrike\cfg.

Only seems to work on yourself though in that instance.