If I understand your question, you want to generate vCalendar appointments from Transact SQL..?
It seems doable, since it can be plain text, though I don't know if it qualifies as "easy". My guess is that you have to construct the proper text message according to the vCalendar specs and then mail it.
The vCalendar spec can be found here.
http://www.imc.org/pdi/pdiproddev.html
/Kenneth