Given that the bottom E and A are two octaves higher,a .010 and .007 will tune to that. The middle two, one octave higher, will need .014 and .008, and the top two, as standard can be .012 and .010. All I've done is calculate each string as a close approximation to a standard open guitar string, given its open pitch. These can be changed by about 10% either way, depending on the guitar and your preferences. I think the Nashville set is only one octave up on the bottom 4, judging by the gauges, and will make it sound similar to a 12 string. The one thing that makes a 12 string sound like it does is the high 3rd string, higher than the rest, but in the middle of the sound.I'm sceptical about the 'low' E and A, though.
Strings can be bought separately at a small premium. I use a weird combination, not available as a set, so tend to buy several of each, to make up my own sets.
Addendum - consensus is that the bottom string is 2 octaves up, but 5,4 and 3 are one octave up - so the gauge for the A will be around .018. That's if my research has found the truth !