Actually, the {keyword} parameter isn't case sensitive in adCenter. Unlike Google's syntax {KeyWord:default value} where the capitalization of the parameter name controls capitailzation of the keyword, adCenter inserts the value of the parameter in the same capitalization as the actual keyword. And no, you can't change the capitalization of the keyword once it's uploaded to adCenter. You would have to delete the keyword and replace it.
There's another solution to this problem that I covered in an adCenter blog post that might be helpful.
Cheers,
Charles
MicroMarketing