seat belt question

[Desertanddune]

installed new seat covers, there are slots in the seat for belts to go through but none in material underneath, what is the best way to make provisions for the belts to go through instead of around the seat like it use to?

 

[megadesertdiesel]

use soldering iron/hot poker to make ends of slots to prevent ripping, and then a razor knife to cut the slot.

like this
0-------O