anything is posible
I had a frame that had a twist. You realy need to think about the process you use, what pressure will be applied to the tubes where the force is to be applied. You don't want any deformation.
I cut some steel gas pipe in laf length ways and used these as lets say mechanical guards, they slipped over the existing tubes. I inserted a hub into the rear drop outs with very large washers. This was just loosely fitted but enough to keep chainstays the correct spacing.
Now the steel bar I used was about 10mm x 60mm. I needed to use it with the force going through the 60mm as the 10mm would just bend. (There are tools you can buy to straighten frames, go to the park tools web site.)
All in all its a daunting process with creaking cro-moly, I needed to go a little beyond my desired as the steel has memory.
But it was a success.
Good luck If you want any more guidence just PM. I did have some pictures of teh process. I will hunt them out.
Current list for sale.
BNIB 26" Mavic Crossmax SLR. PM me
PACE RC200F2 small, incredible condition. See For Sale section
Zeronine Works Pro. ex Pete Middleton. See RADBMX or PM me