Rewriting a single SIMM with specific game data?

[kazuo]

I have a multi with 3S installed; long story short, I had to replace SIMM 6, and I really don't want to rewrite the entire thing... is it possible to rewrite only SIMM 6 with the required data for 3S (990512)?

Looking at the file browser, I see a bunch of folders, and two of them seem to (probably?) be 3S: S1 and S2. I assume these correspond to versions 990512 and 990608, but please do correct me if I'm wrong... next, I see a bunch of files in the S1 directory:

• 93S
• 92S
• 513S1
• 603S1
• 613S1
• 103S1
• 203S1
• 303S1
• 313S1
• 403S1
• 413S1
• 503S1

Gonna take a wild guess that (probably) 603S1 and 613S1 need to be written to SIMM 6? How do I do that? Please do also just walk me through it from the beginning if I'm totally wrong on this haha.
Thanks!