Zend_Gdata_Calendar_EventEntry posting to shared calendars

I've had a good google, and I apologize if this is either the wrong forum, or if the question has been asked and answered, but I haven't had any luck finding it.

I have an application that is talking to google calendars using the php api, i've been able to successfully pull information from calendars shared with my user, but I've not found any information on how to write to a specific calendar -- there are some gentle references to being able to do it, so I know it's probably something stupid that I've missed.

Any suggestions would be greatly appreciated - either where to go looking or even more helpful would be a snippet of code.

TIA,

Tim.