How can i change the steam id on nonsteam CS 1.6

I saw one guy who successfully avoided 5 steam id bans and then took steam id of an admin.

Is there some kind of a way to change the steam id.

Im not banned on any server its just that i want to know.
I found one program(PBdownforce) but my antivirus says its trojan.
The guy who made it says its probably false positive.

Anyway is there any way to change steam id to any steamid i want,not just random new one?