You can have different busy indicator image by trying to override the style in UserWorkForm fragment. You can include your style inside a pega:choose jsp tag where you can have different when rule based on pxobjclass of the primary page.

I think we should merge these threads (https://collaborate.pega.com/question/how-display-busy-indicator-based-casetype), or close one so that all responses are funneled into one ;)