Reach the welcome.jsp or productlist page directly from external applicatio

All,

I created a home page specific to certain users which will have same catalogs(hardcoded) as that of b2b application.This home page will be called from an external application.once the user landed on that page and on clicking of the catalog the user will be redirected to the b2b catalog directly without logging in(as he has already logged into his application)

Need inputs on how to achieve this

Thanks in advance

Murali.K.N