You pass init parameter to a JSP the same as a servlet, using the web.xml deployment descriptor. The key is using the <jsp-file> element instead of <servlet-class>:
Note, however, that you need to call the JSP by its servlet name, which would be %WEBAPPNAME%/servlet/foo, in the case above. If you don't, the servlet engine will not be aware that you are using the <servlet> element with its init parameters.
You can additionally supply a servlet mapping if you still want to use a "jsp" name:
If you've never read the JSP specification or the DTD, it can be of great help to you.
Sun Certified Programmer for the Java 2 Platform
Author of : JSP: The Complete Reference Instant Java Servlets