I've cold set a few frames. I use a 6ft 2X4 and I push down neat the center of the board. I lay the frame on a piece of carpet and prop the 2x4 up on the washing machine. Be sure to keep the end of the 2X4 close to the BB. Steel is springy and you have to bend it past the point where it springs back to where it was. Just keep increasing the force and measuring until you get some permanent movement. Don't try to spread it more than 2mm at a time. Don't use your foot. It takes a delicate touch. I think you'll get a feel for it and the other side will go much faster. Be sure to check the alignment with a string.

I don't think the chrome makes the frame stiffer, but I know that chrome will crack and peel if you flex the frame too much. I don't think that cold setting will put enough bend in it to cause that, though. I found that mixtes are harder to spread because they have an extra stay.

Good luck!