of course it works.
You shoot the target, set C1, as "deja" explained, to "no color correction" (I'd prefer the "linear" film curve but that's up to you) and create a TIF that you load into the profile software. The software creates the new profile.
Now the created ICC profile can be assigned as input (camera) profile in C1 all the time (whether it works good or not so good depends on a lot of things, but that's a different story). You can even use it as camera profile for another camera (what, obviously, doesn't make sense).
If you can't access the profile in C1 you've stored it either in the wrong directory or the profile's table tag "sncr" isn't set propperly. But if so, you can use it in C1.
Ok, now I understand - at first C1 renders the image to that "no color correction" something, and then it assigns the camera .icc profile. I checked it, and you're both right - it works.