This is based on admin_llama. But, instead of a llama, you can make whatever character you want. 

Format is like this: 
admin_char (target) (character) (say1) [(say2)] [(say3)] 

Target is obviously the target (name, sessionid, etc), character is what you're changing their name to, and the different say phrases are what you'll change their speech in to. Only one phrase is necessary, but you can have up to three. 

IMPORTANT - if your phrases contain more than one word, they must be enclosed in single quotes! - '