Murray J. Harris, _Jesus as God: the NT Use of Theos in Reference to Jesus_
(Baker, 1992).
His discussion includes (chapter 6) a 30 page discussion of Rom. 9:5,
including a detailed analysis of the many grammatical possibilities.
Conclusion (p. 172): "It is therefore highly probable that the term QEOS is
applied to hO XRISTOS in Romans 9:5."
Mike Holmes