I know when you lanch from windows you just add -console to the .exe in the shortcut and hit ~ to get to cheat mode but when I've tried that with the Steam lancher nothing happens. How do you add the -console shoutcut to Steam?

This may help:
https://support.steampowered.com/kb_article.php?ref=3041-SHZN-9384

i never added anything to my executable file and have always been able to access the console with the tilde key........

Console is already there, you don't need to add a command to it.