In theory it will work.

The writer of the CTC Shimergo web site explains.

In theory, we ought to be able to predict the overall width of a cassette from sprocket pitch × (n – 1) + the thickness of a sprocket. For some cassettes that works, but others are wider than we'd expect, with the top two or three sprockets spaced a bit further apart. That's not a problem because the first click of the shifter always pulls some extra cable so as to take up any slack, with indexing of the top sprocket provided instead by the mech's high-gear stop screw. The low-gear stop does a similar job at the other end of the cassette, so that only the intermediate sprockets are actually indexed by the shifter. This is part of the reason some "incompatible" combinations actually work okay – at least when new. With only seven out of nine sprockets dependent upon the subtle relationship between cable pull and shift ratio and with indexing set on the middle one, the maximum shifting error is only three times the error per click. If, for example, the mech shifts 4.55mm instead of 4.35mm, the most it'll be out is only 0.6mm, and only in next-to-top or next-to-bottom. The rest of the reason is that the guide pulley can float about half a mm side to side, allowing at least that much misalignment between mech and sprocket without any nasty noises. Add a bit of friction though, plus some wear and tear, so the mech position varies by a millimetre or two depending on whether you're downshifting or upshifting and that 0.6mm may be all the difference between shifting or just sitting there and rattling!
http://www.ctc.org.uk/cyclists-libra...gears/shimergo While I was upgrading one bike from Shimano 9 speed to Campy 10 speed, I tried the Campy shifters with a Shimano 9sp derailleur and Shimano 10sp cassette (for no other reason than to see if it would work). It actually worked, sort of. So if one is not too picky with the quality of the shifts, it will work, but as the CTC writer said, at least when new