As it turns out, it's a cinch to add appointments to PocketOutlook. Open Visual Studio 2005 and create a new Windows Mobile 5.0 SmartPhone Device Application (from the template which was installed with the SDK).
Next, add a reference to Microsoft.WindowsMobile.PocketOutlook:

Now, all you need to do is create some code that inserts an appointment. Put the following code in an event (such as a Click or OnLoad).
If you were to call the AddAppointment method, you would be baking a cake tomorrow for Nicole. Don't forget to import Microsoft.WindowsMobile.PocketOutlook. With just a little bit of code, you can be adding appointments to PocketOutlook!