How about the following simple thing:
For each group, item class equal to "desired class", do stuff.
So you could have a filtered list of classes stored in a Hash Table for example. And then do something like For each key => INI group Hashtable.CurrentValue, ... you get the idea.
On a serious sidenote you would want to limit the number of file operations when dealing with inis. Ideally you'd only check stuff from the INI once on startup. If you need to check back often, you should just load the groups and items from the ini into values. The S plugin can be handy for this. Also as a complete replacement for INI in many cases.