only rich:fileUpload could be used to upload asynchronously.
Thanks for the reply can you please provide me some more information! It'd really help me to nail this issue[File upload using ajax command button].
check richfaces-demo fileUpload sample. http://livedemo.exadel.com/richfaces-demo/richfaces/fileUpload.jsf
And again you can't use inputFile (from seam or tomahawk or any else) with a4j:command. And this is not a RichFaces restriction but just xmlHttpRequest object not allows upload because of security restrictions.