I'd like to know how to do it too. I had Xperia Tipo before and there you could just edit vold.fstab file, but I can't see it on my I9105P...
EDIT: Ok, in case anybody will still need this: to swap internal and external cards just edit the vold.fstab file (which exists only in Android 4.2.2 and lower - I'm running 4.4.2 and it explains why I couldn't find it).
Hmm, that's strange, I remember that when I did something wrong with vold.fstab on Tipo I could just restore original file it just simply didn't swap the partitions (I wasn't trying to edit vold.fstab on s2+ just because I flashed cm11 a few hours after I got it for Christmas).
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