As has been pointed out elsewhere in this thread earlier versions of ExtUtils::MakeMaker (and probably Inline::MakeMaker) didn't support the CONFIGURE_REQUIRES directive

The critical thing would be the version of the cpan module being run by the user, and the version of EU::MM that the user has installed.

Inline::MakeMaker is just the hapless module that needs to be present.
It should just ignore the CONFIGURE_REQUIRES - which should be fine. By the time we get to the stage where Inline::MakeMaker realizes it doesn't know what CONFIGURE_REQUIRES is, "CONFIGURE_REQUIRES" will already have served its purpose (if all goes as planned).

Anyway, let's see if that works.
Here's hoping :-)

Cheers,
Rob