The purpose of doing this is to ensure that the workflow is calibrated
from camera to digital file, basically the first step of the process.
While it is true that calibrating is *really* only good for the
lighting setup under which the image was made, a calibration using
color-balanced lights (measured with a calibrated color temp meter)
will give you a better starting point for your camera than the built-in
profile. How much better? Not too much, but noticable in my experience.
Most cameras have slight color shifts of their own, and if you've
reason to be anal, you can eliminate them.

Depending on the workflow, this step, along with monitor calibration,
is enough to have a color managed workflow for digital-only images.
Profiling your printer is the next step if you want to go to print.

Obviously, a calibrated monitor is most important, because at least
then you can be confident that what you're seeing is what you've got.
But in some cases it might be important to know that what you saw when
shooting is where you'll start from in post. Shooting ads for
Coca-Cola, for example, where much money is spent ensuring the fidelity
of the red used, would be a time to profile your camera.

True story: Coca-Cola's ad people (for commercials) will come into a
color correction suite with a machine-cut stencil to place over their
own vectorscope (used in the video world to track chroma values).
There's a small hole where "Coca-Cola red" should fall, and they always
check to make certain that it does.

As for the original poster's question: I don't think I can ethically
give you this information, but you can find a good, easy-to-follow
workflow in Bruce Fraser's "Real World Camera RAW with Adobe Photoshop
CS2" from Peachpit Press. And it is a great reference as well.

Will

Yes, I think you might be missing something.

I want to calibrate my ACR. According to the procedure for ACR-Calibrate one
takes a photograph of the color card. Then using the photograph of the color
card, a profile is built for that camera. If there was a version
ACR-Calibrate that handled ACR 3.6 (I need 3.6 since I have a Canon 400D) I
woulnd't need to be asking this question to begin with.

Afterwards, a color card is included at least once during every photo shoot
since the lighting will always be different.

One person on the Internet said that he bit the bullet and entered the colors
by hand into Photoshop but I haven't figured out how to manually enter color.

For example, white is 243,243,242. Black is 52,52,52 and green is 70,178,149.
 Where do I enter those colors?