Hi Craig,
There isn't a simple way to use the class command to do a case insensitive match if the data group entries are in mixed case. You could loop through the data group entry by entry manually and set the data group key to lower case. But that's extra complexity and overhead you could avoid if you just add the entries in lower case and set the string you're looking up in the data group to lower case.
As an extra precaution, you could use a script called from cron to update any mixed case data group names to lower case via iControl or tmsh.
Aaron