Jimi,
If you put a 10" trout in a plastic Ziploc bag for 45 minutes or so, you might get enough fish slime to scent your entire mouse colony
. I doubt you'll have any trouble converting them with trout onhand. Just wash the pinkies first. Then scent them, and mix them in with fish chunks, so the snake is surprised by its first mouthful of a pinkie.
Rick