I actually just used my Rikktor killer soul glaive on the golem. It's 30 DI, HML 37, HSL 44, Dragon Slayer, 30 SSI, 60 cold/40 energy. Worked great, popped consecrate now and then.
I think I agree with obsidian, 100% cold is so hard to make its kind of a waste to make one for these critters.
If you special craft a 100% cold killer I would maybe leave 1 imbue slot "blank" for slayer so that you can turn it into a rikky/stygian dragon killer or use it for another purpose when the golems are gone. Daishos are fast enough that if you put SSI on your suit, like turq ring+tinker legs etc, that you don't need SSI on the daisho.
Or you can probably easily make a partial cold killer by doing the following. Use DC runics and find a daisho which has partial cold and physical. Then enhance it with shadow for +20% cold or agapite for +30% cold and +20% energy. You'll end up with a weap which is 40-60% cold, which is pretty nice, you won't have to pop consecrate as often but won't have to spend weeks crafting. Agapite is counted as a double enhance so double chance of failure btw, wear an ancient hammer.