[JAMF]

Guessing the steps:
Fish around the with the SFS extractor to find the object I want?
Convert to 3DSMAX with MSHConverter?
Edit with 3DS Max?
Export with Buggy-buggy exporter?
Repack the SFS with?
Package my mod by doing ?

I think that you dont need to make it SFS again

Correct.

Guessing the steps:
Fish around the with the SFS extractor to find the object I want?
Convert to 3DSMAX with MSHConverter?
Edit with 3DS Max?
Export with Buggy-buggy exporter?
Repack the SFS with?
Package my mod by doing ?

You'll need to check if your meshes end up where they belong, so you'll need to check in game and correct the positions in the hier.him. If you check other mods, they follow a certain structure... well, they should anyway.