Adding/Removing map services in TOC *

Hi,

We are using two different map services in an application.

I wanted to know, Is it possible to create a workflow - when clicked, one of the map service must be invisible in TOC (dataframe).

and when clicked another workflow - the map service must reappear in TOC(dataframe).

If you so, could you please provide as what I should use?

Thanks

Srikanth