You don't. Firstly, any object that is in scope while the JSP is executing on the server goes out of scope as soon as the response is sent to the client.
Secondly, the HTTP protocol limits you to submitting strings as request parameters via a form submission. No objects -- no nothing, except strings.
Perhaps this article on the life-cycle of JSP pages will help you understand these concepts.
If you want/need a server-side object to have a scope greater than the lifetime of the current request, you will need to explore alternate means to do so. Perhaps as a scoped variable in session scope?