Sorry if this is a dumb question, but do you have a psp of your own that you can use? Because to my knowledge (and from some searching on google), I can't find anything that will enable you do it on a card reader. Did you try Rain's Simple MMS Maker? I'm not sure if it will do anything but it's worth a try.
http://www.maxconsole.net/forums/sho...d.php?t=122340