I could see you have two options, either use the outlook activex or access outlook directly via automation. But may I ask why you need to "register a toolbar with Outlook".
Here is an example of the first option
http://www.tek-tips.com/faqs.cfm?fid=3808


>Does anybody know how to create a toolbar which I can register with MS Outlook upon installing a VFP app ?
>
>The toolbar need to automate processes like creating contacts and messages in the VFP app.