Add them to a shared stream and invite yourself as a subscriber (see http://help.apple.com/icloud/#/mmc0cd7e99). Also, just so you are aware, photo stream photos only remain in iCloud for 30 days, giving your devices time to download them. After that they are removed. If you ever disable photo stream on your phone, then turn it back on, you will lose any photo stream photos older than 30 days. If you want to keep photos in iCloud indefinitely, add them to a shared stream.