Most likely. They offer the 6-speed on the normal SLK (as they do on the Crossfire) But not on the SLK32 AMG.
Both the regular V6 SLK and Crossfire are just over 3000lbs (like the Z06), but the S/C version of the Mercedes convertible (SLK32 AMG) is 3225lbs, so it's likely that the S/C Crossfire will weigh the same, and offer the same performance (0-60 in 4.8, 13.3@ 104MPH) as the SLK32 AMG.
With the Crossfire priced around $33,500, it's around $12K less than the standard SLK. So it figures that the S/C CF would be priced at around $12K less than the SLK32 AMG (at$55K), so potentially that would put the S/C Crossfire around $43K.
I do get the feeling that the S/C Crossfire is positioned to be more of a luxury sport convertible. Between the $38K Thunderbird, and the $62K Lexus SC430, rather than against the Corvette.
-Dean.