Hi,
It's a bit unclear which version of Sybbase you have? But Sybase supports EF in their newer versions. In Anywhere it's from 11 and up. I'm currently using this in the current job I have.
As for EF 4.1, i'm guessing you want to use CodeFirst/DbContext? Since DbContext is an abstraction over ObjectContext, I guess that it should work, but I haven't tried.
--Rune