I didn't understand very well your problem (wasn't clear)
If what you need is case insensitive commands through the chat
Try this plugin from Dragokas
[ANY] !COMMAND eater
Is very good and it does that. (and more things)
I have a private version based on what Dragokas made (more simple/less features), if it doesn't work, PM me, in case what you want is insensitive commands through the chat.
Otherwise, please explain again in another way.
If you need that insensitive format by console maybe Dragokas have an answer for you or even modify his plugin to support this (if possible)
Edit: I did some tests and in L4D2 for example console commands only works in lowercase, I don't have this behavior of typing "Sm_Slay" and working.
Which game you are testing?