Portal - optionset

I have a Optionset that I am displaying on the portal form.  Once of the labels needs to be Dynamically changed.. 

 index 1 -- label -- Apply as Exhibitor

 index 2 -- label -- Apply as Individual

 index 3 -- label -- Apply as Group

Apply as exhibitor - label need to be dynamicall changed depeneding on a role

if Role = admin

 label = Apply as Exhibitor ( your will need to add the invited code)

if role = user

  label -- Apply as user (you will need your email)

and so on.. IF there a way I can change the label , Please .

THe value in the brackets needs ti be ITalic and in Red.

Thanks

Bik