Export from Webpage to a Lotus Notes Appointment

My company books hotels for business travellers, who can log into our website to view a list of hotel bookings. Our website is written in ASP.NET (VB) on Visual Studio 2005.

We have had two of our large clients request the facility to able to click on either a button or a hyperlink next to a particular booking that would automatically insert it into the Lotus Notes calendar as an appointment.

What method(s) could I use to do this?

I have found a company at www.infuser.com that can do this via a hyperlink and software the client downloads for free, but this would cost us between $750 and $25,000 per year to license. There surely must be someway I can program this myself.

Note: We do not have Lotus Notes at our offices.

Any assitance would be greatly appreciated.