Supposing your uniform template GUID is 00290B6F. You put the '0029' on the first line, and '0B6F' on the second line.
How to make a new school uniform setter
The Simlogical school uniform setter works with the Simlogical school bell to change the children into a uniform of your choice.
1. Make a new school uniform template, using the instructions here. Make a note of your template's GUID.
2. Clone the Simlogical uniform setter and give it a new GUID. You can change the mesh or recolour it; and if you know how to code init BHAVs you can make it be something other than a wall hanging item if you wish.
Supposing your uniform template GUID is 00290B6F. You put the '0029' on the first line, and '0B6F' on the second line.
4. Commit and save. Your new uniform setter, your uniform template, and the outfits listed in the template (unless the outfits are Maxis originals) all need to be in your Downloads folder.