Hi Evvo1961 and welcome,
There is an ical format and you can have InfoPath send email messages in that format which would then show up as meeting requests. In addition, you can write code to call Outlook object model and add the request when they click a button and then synch it to SharePoint. Or, if you want just SharePoint, you could call the Web Methods that SharePoint exposes for adding items to it's calendar. Lots of options but all require code. We do providing code consultation for people and have hourly rates between $30-120/hour, depending on what level of expertise you need. If you're interested, please go to Qdabra's contact page and fill out a consulting request.
Cheers!