In your sentences, I would say them as a hearing person the same way you would in asl if you switched it a bit into more of a question. I don't know if that makes sense. For instance:
"I didn't say YOU stole it" is sort of a 'who' statement and I would drop/purse my eyebrows when saying YOU just like if I asked 'Who stole it' in ASL.
"I DIDN'T say you stole it" is more a yes/no statement (Did I say you stole it?) and I would raise my eyebrows when saying Didn't.
That's just how I would naturally say them though, and don't know if those rules always apply or anything, just trying to help out.