There is actually no way in OPC to achieve what you have indicated. This is because the interpretation of the item IDs is entirely left on the OPC server, with client having no information about their syntax, including case-sensitivity.
Regarding the ElementNameCaseSensitive parameter:
This parameter applies only during browsing, and only in somewhat special case. For browsing, there is a parameter where you can specify a name filter (a string like "AB*", for examples), and the browse operation would return only the items that match the filter. In newest OPC DA specification (3.0), this filter is passed to the OPC server and interpreted there, giving us no choice to influence how it is interpreted. If your target server happens to be OPC DA 1.0 or 2.0, then there is (generally) no name filtering guaranteed to be implemented on the server side. We therefore get all the items from the server, ad then post-filter them on the client side. In that case, you can influence the case-sensitivity of that filtering using this parameter. Note that other aspects of browsing (such as case-sensitivity of the parent node ID passed to the browse operation) are not influenced by this parameter.