If you're referring to the ics files that can be included in an email, I've been doing them in Pan 6 and now in Pan X. It's not as complex as the reference you found, but more than a quick post here would cover. I got it working originally by reverse engineering the internal structure of ics files created by other apps, then using Panorama to handle the data and save it as a .ics file, and it has worked very reliably.
Without explanation, here's my code for it. Okay, I will explain that "fg" designates a file global with those values coming from a Panorama form.
Local lviCal, lvName, lvFolder
lviCal = “BEGIN:VCALENDAR
lvName = datepattern((fgStartDate),"YYYYMMDD")+“-”+Timepattern(Time(fgStartTime),"HHMMSS")+".ics"
savefiledialog lvFolder,lvName,"Save as..."
You can also interface with the Mac Calendar app quite readily using Applescript. Although it's old, the info at this MacTech page is still valid. I use it to set appointments in my Calendar with reminders or anything else offered by Calendar.