@adamg, good luck. As far as I can tell, the Apple Calendar is extremely limited, as compared with something like MS Outlook Calendar. I don't even see a way to get a reminder for when a Calendar event is about to occur. Even the iOS Calendar is better!!!
If it were me, I'd look for a better Calendar tool.
Here's an idea:
- Use Apple Reminders instead of Calendar.
- Put the URL in the Reminder notes
- When the reminder pops up, just click the link
Something like this:
The above is both the display when you enter the reminder, and what is displayed when the Reminder notification pops up, and you click on it.
Simple, easy to implement.
Also, Reminders are scriptable.