I do not understand what you can have in mind.
The keyboard driver knows nothing about ISO-8859-1.
Many people are using it with ISO-8859-2, for example, but
also much more exotic character sets are in use.
The distinction is not ISO-8859-1 versus non-ISO-8859-1, but
single-byte versus UTF-8.
Maybe you can clarify what you want to do, and why the current setup
is unfortunate for your purposes?
Andries