Good to hear it works. I would have used a bracketed character class like [\\\/] but it turns out that a sequence of delimiters is treated as individual characters so that's unnecessary. It's in the docs now that I read them, so the rest of the post is partly for reference by my future self.

print $RE{delimited}{-delim => 'ab'};
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gives

(?:(?|(?:a)(?:[^\\a]*(?:\\.[^\\a]*)*)(?:a)|(?:b)(?:[^\\b]*(?:\\.[^\\b]
+*)*)(?:b)))
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If one uses a character class then the square brackets are treated as delimiters.

print $RE{delimited}{-delim => '[\\\/]'};
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gives

(?:(?|(?:\[)(?:[^\\\[]*(?:\\.[^\\\[]*)*)(?:\[)|(?:\\)(?:[^\\]*(?:(?:\\
+\\)[^\\]*)*)(?:\\)|(?:\\)(?:[^\\]*(?:(?:\\\\)[^\\]*)*)(?:\\)|(?:\/)(?
+:[^\\\/]*(?:\\.[^\\\/]*)*)(?:\/)|(?:\])(?:[^\\\]]*(?:\\.[^\\\]]*)*)(?
+:\])))
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...and a RegExp object appears to be stringified and then treated as a sequence of characters.

print qr'a';
print "\n\n";
print $RE{delimited}{-delim => qr'a'};
print "\n";
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gives

(?^:a)

(?:(?|(?:\()(?:[^\\\(]*(?:\\.[^\\\(]*)*)(?:\()|(?:\?)(?:[^\\\?]*(?:\\.
+[^\\\?]*)*)(?:\?)|(?:\^)(?:[^\\\^]*(?:\\.[^\\\^]*)*)(?:\^)|(?:\:)(?:[
+^\\\:]*(?:\\.[^\\\:]*)*)(?:\:)|(?:a)(?:[^\\a]*(?:\\.[^\\a]*)*)(?:a)|(
+?:\))(?:[^\\\)]*(?:\\.[^\\\)]*)*)(?:\))))
[download]