Actually, I think you are missing a step.
In order for Conform to alter you clip, you will need to put it on a timeline that has a diffent frame rate.
If your clip is 59.94 fps (60), your project settings should be 29.97 fps.
Then, when you drop your 59.94 fps clip into the 29.97 fps timeline and choose Conform, FCP X will slow the footage conform the footage to 29.97 fps. If you open up the Retime Editor, you should see a value of 50%.
While I've searched and read a fair amount on the topic of Conform, I'm not sure I fully understand it. Especially when I test it in FCP X.
I don't understand the difference between conforming a clip from 59.94 fps down to 29.97 fps and/or simply retiming a clip (a 59.94 fps clop in a 59.94 fps timeline) to 50%. The seem to produce identicle results. So, I'm not sure why you would do one over the other.
At least in terms of slowing down clips shot at 60 to either 30 or 24 fps. Which is to slow them down to either 50% or 40%. Also, in testing both retiming and conforming both to both of these produces what appears to be idenical results. By that I mean when I compare frame by frame a clip that is conformed from 60 down to 30 and 24, the frames seem to be identicle. Granted I didn't compare every frame, just several samplings. Wouldn't going from 60 to 24 produce either new, or interpolated frames?
Would either of these methods make a difference if your final output was DVD? (Bluray) I haven't actually tested it, but I guess it would be interesting to see if you could tell the difference between the two. Either way, I'm at a loss as to why do one or the other.
Am I missing something in the editing aspects of the two approaches? They seem to behave in a similar fashion. Editing either on a timeline seems to be the same. Adding or removing frames anyway.