You could probably get at it with something like:

use Cwd;
use File::Spec;
print "In directory ->", File::Spec->catfile(cwd(),
    '..\admin\templates'), "<-\n";
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However, the problem may be that TT2 expects colon-delimited directories in INCLUDE_PATH. You can also pass an array reference, or set the DELIMITER option so it expects the semi-colon. Give that a whirl.