Não de maneira compatível.
Extensões suportadas para o Microsoft Dynamics CRM
Form Scripting
Microsoft JScript functions that are associated through the customization tools to the available events in the form are supported. Interaction with data in the form is supported when performed using documented objects and methods available within the Xrm.Page.data object. Interaction with the form appearance and behavior is supported when performed using documented objects and methods available within the Xrm.Page.ui object. However, any direct interaction with the HTML Document Object Model (DOM) will probably not be upgradable. The structure of forms and HTML elements used in the forms could change in future releases. For more information, see Write Code for Microsoft Dynamics CRM Forms.
E, até onde eu sei, o Xrm.Page.ui não suporta esse tipo de funcionalidade.