I think the description line says enough. I've tried putting them in the app itself in Contents/Resources/ but they don't seem to be recognised from there. It's not worth whatever the "buy support" side charges to ask one question of this small magnitude, after which I am quite satisfied with the application.
Puzzling it out as I'm writing this, it occurs to me that the codecs may be seen in ~/Library/ApplicationSupport/Switch/ instead, if such a folder is created on the first launch of Switch in Mac OS X. If not, I'll create one, cross my fingers and hope. Perhaps my having seen a Unix binary for lame in that other location was a program-specific fluke and the others don't follow that pattern, being add-ons. Yet a Mac user would be hard-pressed to find this anywhere on the site pages for Switch, and certainly no such advice or tips appear on the download page/s for the codecs. This ought to be changed, and yesterday!
Thanks for reading my post.
Have a day
BZT