How to implement "Switch to another Personnel Number"

Hi

I have a requirement in ESS - certain users must be able to raise a travel plan request on behalf of other users. Now I know there is an application called ChangePersNo in ess_tratri DC in ESS, but how can use that? Where do I have to use it?

Should this application be triggered from portal? Or should I incorporate it in webdynpro?

Could someone please give me more details on how I can implement this?

Thanks.

Manoj.