Observe Richfaces events with Prototype

[migelct]

Hello,

Is it possible to observe the richfaces events with Prototype?

With a normal event:

$$("select").invoke("observe", "change", activateAutoSave);

WIth a RichFaces component, I have tried, but it doesn't work:

$("portalForm:upload").invoke("observe", "upload", activateAutoSave);

$("portalForm:upload").invoke("observe", "onupload", activateAutoSave);

I'm using Richfaces 3.3.3.

Thanks in advance.