I've converted 5 FL55/1.2s and one FD lens, if that is where your interest is. FDs and FLs are certainly difficult and varied in their back construction, but I've noticed one interesting thing. Whether by Canon design or chance, the bolt pattern of the FL55 and some FD lenses are exactly the same radius as the EOS shank that fits into the camera throat. I'm refering to the 3 or 4 screws that secure the FL and some FD mount backs to the lens body. The benefit to this, is the 2mm by 2mm shelf of EOS shank is just enough to hide the profile of the screw heads. No worry about countersunk flatheads thru a thin wall adapter face.
So at least in this case, the key to a good conversion is drilling accurate holes thru a M42-EOS adapter and using the original lens screws. Infinity can be adjusted with the lens focus stops, but I cut down about .5mm and got pretty close to the original focus ring position.
I don't know if this could help, but here are some photos taken when I have tried to convert my 50mm f1.8 fd lens (I was curious to see if I could do it). Its not complete yet, the lens can only focus up to 3 meters.
theophilus wrote: Are there any instructions out there? Specifically looking at the 35 T/S and 55 1.2.
Yes, you need lathe and the way to convert the both lenses are totally different.
The both (FD TS 2,8/35mm, FD 1,2/55mm ssc aspherical) are sucsessfully converted to EF mount by me ( use 5D body).
If you mean Canon FD 1,2/55mm (without rear element) , I think it is easier to convert than Canon FD 1,2/55 SSC asph (with rear element),
The last was difficult to get infinity focus at wide open and only useable with shaved mirror on 5D.
If you have interest to see the result of the both lenses ,please have a look at http://www.flickr.com/photos/convert1/
Over there are list of "my destroyed Canon FD and Minolta lenses".
Best regards