That (the indirect object syntax, not the missing space) looks like a parsing bug. I managed to get things to work with:

BEGIN { @*INC.push( 'C:\Rakudo\lib' ) };

You might want to ask on #perl6 if this is a known bug.

Update: parenthetical note added.

In reply to Re: Perl 6, modifying @*INC by chromatic
in thread Perl6, modifying @*INC by molecules

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