I don't know if any vanilla conjuration spells use scripts, and I'm not familiar with any magic mods of how they handle it.

You can just try to locate the spell in question in the CK, find the script it uses, and look at that script. All scripts are in the /scripts folder.

Decompiling an actual .pex file won't necessarily get you anything readable, though... you'd be better off either finding a .psc file or asking for help from the mod author. Source files are in the /scripts/source folder.

What mod and what spell is it exactly you want to look at?

Any summon spell like atronachs will work.