Hmmm.. Im not sure, but I think you could use AS 3.0 camera and the Bytes object (im not sure of the name) to actually store the picture in a temp file.

Anyway is not needed, in regular As2.0 create a camera object, copy that surface and then use copypixels (or a draw) to use it as an sprite. I think I have some code here on how to store your camera image (for "motion sensing" purposes)

edit: OOps! you meant without a camera. Is simple just use a web form to upload a file, there are more complicated methods but you dont need anything else.