I am just back from a holiday in the Seychelles.
I flew an Air Seychelles Twin Otter from Mahe to Bird. Interestingly, they had Garmin 430, as standard kit.
For the strictly VFR islands, they had approach fixes linked into the 430. It appears that they depart Mahe, commercial ops, in IFR, then convert to VFR as they approach the islands, head to an approach fix, which has been built in, and this is the approach set up fix. I assume if they are not visual or VFR, then they go away.
Perhaps someone more familiar could confirm, or not, but they definitely looked like self made fixes.