I am also having id mismatches. I've attempted to simply drop it into the mods folder in my v6 Mindcrack server. Server starts up, but when my client (which also has mystcraft zip added to mods folder) attempts to connect, I see 4 id mismatches and it does not allow me to connect.
How did you set up your v6 Mindcrack server - did you run into any issues?
How did you set up your v6 Mindcrack server - did you run into any issues?