For allies/owner NO,for enemies use Animation-Vertex Color(hope i spelled it right).But you can make illusion "Neutral-Victim"(so that its not players ally),and make a custom illusion AI trigger(don't know how,but for example,make that when the illusion is clicked,another,dummy unit ( a 100% transparent unit with no shadow), is selected for clicking player,and when the dummy is ordered something make the illusion copy the orders),its not a perfect idea,but can fill in.
Idea NO2: Make a identical copy of the hero/unit,and add it illusion tag from triggers,this idea isn't too good either but,depending on how you want illusions to work,it might do the job.