Cheating in L4D (Please Help!!)?

Ok so me and my friend play for fun not for points. In CS we would play all the time, just us, with codes. (I NEVER cheat when playing online.) So, i got L4D, and i just wanted to know that if i start a LOCAL FRIEND ONLY SERVER with just me and my friend (The rest being bots) and i use cheat codes in the console commands (e.g. z_spawn tank and spawn witches and stuff like that) will i get in trouble and get banned from Steam?