Now if someone can tell me how to get a Macbeth color checker to magically turn into a color profile in C1...
If "magically" means "automatically", then you need some software other than Capture One.
The procedure is:
1) Get the image into Capture One.
2) Be sure to select the film curve you intend to use together with the profile.
3) Process the image with the color profile "Embedded". 16-bit TIFFs are STRONGLY recommended.
Now use your favorite color-profile-creation-tool to build the ICC compatible with Capture One.
* * *
Creating color profiles is a black art. Personally I don't think a profile created from a simple color checker is very good.
If your goal is to measure the colors (e.g. sometimes a requirement for museums), then you should use a linear filmcurve.
The image will be flat and dull, but accurate, which is often what you want in reproduction. In photography, not so much.
In Capture One you can use the color editor to create the color profiles manually. While it is quite a bit of labor, it can give better results.