you don't lol
no matter how hard you try, even with rally points, you won't get a cast photo like that on the bridge sadly... wish it was an option to get it done somewhere, but it's not...
the quick way i do it is to use the costume design area, take screenshots there and you have a nice dark background to cut out, just ignore the annoying stars lol... then just blend the pictures together in an image editing program
thats the only way i know of to do it, i did try using rally points for a while to get a good crew photo for away missions and stuff, but it just couldn't be done
M