Have you tried something like this? It only works if you have some random trash spell that you can throw in between to use up a global cooldown. Anything works - I just find the cheapest spell that doesn't have a cooldown.

Of course, you would run into issues with sync'ing them all up if, for example, you press this before the 30 min SS cooldown is up

/target <priestname>
/castsequence Create Soulstone, Minor Soulstone, Find Minerals, Find Minerals, Find Minerals

/target <priestname>
/castsequence Find Minerals, Create Soulstone, Minor Soulstone, Find Minerals, Find Minerals

/target <priestname>
/castsequence Find Minerals, Find Minerals, Create Soulstone, Minor Soulstone, Find Minerals

/target <priestname>
/castsequence Find Minerals, Find Minerals, Find Minerals, Create Soulstone, Minor Soulstone



Or you could try something like:
/target <priestname>
/cast Create Soulstone
/castsequence Minor Soulstone, Find Minerals, Find Minerals, Find Minerals

/target <priestname>
/cast Create Soulstone
/castsequence Find Minerals, Minor Soulstone, Find Minerals, Find Minerals

/target <priestname>
/cast Create Soulstone
/castsequence Find Minerals, Find Minerals, Minor Soulstone, Find Minerals

/target <priestname>
/cast Create Soulstone
/castsequence Find Minerals, Find Minerals, Find Minerals, Minor Soulstone



Final alternate (since I don't really know how soulstones work as items and not spells, the above two might not be ideal)

/target <priestname>
/castsequence Create Soulstone, Find Minerals, Find Minerals, Find Minerals
/use Minor Soulstone

/target <priestname>
/castsequence Find Minerals, Create Soulstone, Find Minerals, Find Minerals
/use Minor Soulstone

/target <priestname>
/castsequence Find Minerals, Find Minerals, Create Soulstone, Find Minerals
/use Minor Soulstone

/target <priestname>
/castsequence Find Minerals, Find Minerals, Find Minerals, Create Soulstone
/use Minor Soulstone