$ tar -H ustar -c recovery.img > recovery.tar
$ md5sum -t recovery.tar >> recovery.tar
$ mv recovery.tar recovery.tar.md5
Now you can flash that recovery.tar.md5 through Odin in the PDA tab. Im guessing you can use the same process on any .img file (userdata.img, etc.) you create but i havent tested that. Ive only tested this on recovery.img and it works great.
Sorry if this is old information but i couldn't find any posts in the Skyrocket section and just wanted to share this.