I've tried the Forrs and Rags Gardner Script and for me neither gave great results, however I found doing a manual calibration has definitely improved colour accuracy over the Lightroom default for my camera (a 5D). Here's a quick summary of what I did:
Photograph your target on a sunny day at mid morning somewhere with neutral colours. Spot meter off patch 22 for exposure. Open in Camera Raw, leave exposure at 0, set brightness so patch 22 is correct (I used the sRGB numbers that come with the target). Fiddle with the contrast and shadow settings until th black patch is correct and the patches either side of 22 are equally close to what they're supposed to be as each other (you won't get that close) i.e. they're supposed to be 160 and 85 - I got mine to 167 and 92. The white patch will be lower than it's supposed to be. I ended up with brightness 29, contrast 9 and shadows 3.
Next adjust the red, green and blue patches until they're as close as you can get them to the target. For example the green patch is supposed to be 70, 148, 73 I ended up with 73, 151, 76 (i.e. relationship between r,g and b is right but all are 3 high). Start by adjusting the green patch till it's balanced using green hue and sat sliders, then blue, then red and then repeat until they're all as close as you can get them ( doesn't actually take that long once you get the hang of how the sliders work. Check all the other patches and they should all be pretty good. Note down the numbers for the cal sliders transfer to light room and save as a preset. Test them on a few real life photos and see what you think.
Exposing for the neutral grey patch and then only adjusting the brightness slider should mean that the brightness setting is approximately right to get a normal tonal response from your camera. Also with the contrast setting, adjusting it without adjusting the exposure or using a curve should mean this setting is as close to the correct tonal response for you camera possible. Therefore I also used the brightness and contrast settings as a starting point as I think this gives the most accurate pics you can get however thats not what you normally want so usually end up boosting contrast.
Some people will also say using sRGB rather than ppRGB is not a good idea but I tried both and sRGB definitely worked better, non of the colours are out of gammut so it shouldn't really matter as long as the numbers for each are correct and as the sRGB numbers are the ones supplied with the chart I figured these are more likely to be right.
Hope this waffle helps!
Most of this method is based on Rags Gardners site but I didn't find his script did a great job.