Yes, you can. But let's save you save after it's on slot 10. It'll overwrite slot 1..
But anyways,
1.) Rename the file so that last number is the number of the save you want. (BLUS/BLES whatever the code is-SAVE0000->SAVE0010)
2.)Open an SFO edit
3.) Load the file and edit it, so that the thingy matches the file name.
4.) Resign it. And it should work!
PS Sorry for not being very descriptive, when I get back home, I might edit it and make it more specific