pop up form

I need pop up the pre_entry form, but I cannot use link_to because I
need submit the values to load the Pre-entry form. Anybody have an idea
to help me?

thanks

view:
   ...
<%= submit_tag "Pre-Entry"%>
<%= submit_tag "Submit"%>
[<%= link_to "Cancel", :action => "new" %>]
...

Controller:
  def submit
    if params[:commit] == "Pre-Entry"
      render :action => 'pre_entry'
    else
...