Vista - Set Control Position depending on Date (for custom TimeLineControl)

Hi

I try to build a custom TimeLine WPF-Control.
Based on http://janusys.com/janus/library/Cus...imelinenet.htm
Why: Because Janus dont will build a WPF Version in the near future.

Now I'm looking for a function to calculate the Position for the
Appointment-Item.

UI Example:

[August 2008]
[Thusday August 08]
[0 1 2 3 4 5 6 7 8 9 10 .....]
[ [Appointment-Item] ]


Thanks
Horst