If projects are placed in a public group, you can achieve this, but if you have authentication required for your Jive instance, then this will trickle down to the project as well. To get the data public, you will need to use a service user.
I would recommend though to take a look at our task management solution for Producteev.
There is an extensive API that allows you to do this level of display:
It has been proven at building solutions like this. Hope this helps. =)