Tiamat's kernel has many more slots than IMO's, also different kernels will work differently with undervolting/overclocking. I believe tiamat does have interactive as an option. You could set your max clock speed to 1408 or close to it. Then the following are the slots and voltage under IMO's extreme that I told you to set
245760 : 820
368640 : 900
768000 : 1000
1024000 : 1100
1222400 : 1125
1408000 : 1175
Keep in mind one kernel may run better or worse than the other at the same slot with the same voltage. If you set a voltage and get a reboot you need to up it. You may find it easier to use incredicontrol to set voltage because it has a GUI. SetCPU would work for the overclocking I think there is also something within the rom itself that would allow you to overclock.
245760 : 820
368640 : 900
768000 : 1000
1024000 : 1100
1222400 : 1125
1408000 : 1175
Keep in mind one kernel may run better or worse than the other at the same slot with the same voltage. If you set a voltage and get a reboot you need to up it. You may find it easier to use incredicontrol to set voltage because it has a GUI. SetCPU would work for the overclocking I think there is also something within the rom itself that would allow you to overclock.