Sharepoint Tips And Tricks is Ishai Sagi's sharepoint information blog. It specializes in Microsoft SharePoint technologies, including web parts, development, configuration, customization, and best practices for the use of Microsoft SharePoint Server and Windows SharePoint Services.
It also provides some related Office Information, including VSTO and VSTA and other office application development tips.
After a lot of research, I couldn't find the answer, so I wrote one myself.
To change a person field in sharepoint that is configured to allow "users and groups" to only allow groups, you need to inject code that changes the picker settings after the page is loaded.
//wait for the initialisation of the sharepoint script