It's not possible and I personally do not recommend to do such things as it's easy to make DOS attack by requesting 1 trillion size gradient. That's the reason why framework crypts parameters.
Well, I'm pretty sure you could stop DOS attacks with a little effort, I'm not concerned with them at all at the moment as I am behind a firewall and only the internal network has access to my application. So, I would still be interested in being able to achieve my goal. But you do have a valid point and I would definitly need to consider it before I ever published an application to the web.
I've checked over the code again. In principle, you can implement such functionality if it's needed. Check org.ajax4jsf.resource.ServletResourceContext, org.ajax4jsf.resource.FacesResourceContext, org.ajax4jsf.resource.Java2Dresource and related classes for more.