Hello Jan,
That isn't possible currently within the Custom Organ Design Module (CODM), I'm afraid, but I'll log as an enhancement request that you would like it to have that ability.
(If instead using the 'full ODF format', rather than the CODM itself, it is possible to do that via the Switch.AccessibleForInput/Output attributes. However, if you want to go down that route then I'd need to leave you to experiment, since the full ODF format is potentially very complex and we only officially provide support for editing it to major sample set producers.)
I hope that helps, at least to some extent!