Sure, it's straightforward.  Each XML element is a JSON array whose first element is the element name as a JSON string, whose second element is the attribute mapping as a JSON object, and whose remaining elements are the content as JSON strings or arrays.  The attribute mapping can be omitted if it is empty.

Thus:

<foo/> => ["foo"]

<foo bar="baz" zam="quux"/> => ["foo", {"bar":"baz", "zam":"quux"}]

<foo>32 <dog/></foo> => ["foo", "32 ", "["dog"]]

<foo bar="baz"><dog zam="quux"/> => ["foo", {"bar":"baz"}, ["dog"", {"zam":"quux"}]]