Theme switching

Hi,

       I have developed a plugin which can display all my theme image. Now i need to make a  live demonstration of each theme. I have created a link 'live demo'. But problem is if i enable the selected theme on the same site, the whole site apprience change for all users. I think this way is not fair. Do you have any idea adout this issue?

(Now i think , another way is,  make an another elgg instalation , add link to this and make theme changes on this site. What is your opinion?)

If you have any idea Let me know

Rgds