How to link a MySQL Table with a binary key into Access?
I solved this by creating a updateable VIEW to the table. The view displays every column but the primary key LNEr is converted to a string with the HEX() function:

CREATE VIEW v_ereignisse AS SELECT HEX(LNEr) AS LNEr, Datum, StatNr, ...


In MS Access instead of creating a link to the table I created a link to the view. Because the view has no primary key, the "table link manager" asks for selecting one, this (of course) is the string version of LNEr.