[Lightroom/PS] getting the correct colour

So, I have a pickle to deal with and very fast... [as it is always, heh].

Do you know the fast and accurate way to solve this one:
Couple images are given for post processing. Everything is off, exposure, WB... In every pic there is a logo banner displayed [apart other thing. We know, what the color of the logo is [Pantone, CMYK, RGB values]. What would be the easiest way to achieve the correct color representation in the photo using Lightroom or PS?

Any tips?

PS:

Curve adjustment layer.
Shift+Cmd click on the "known" colors (in newer version of PS, you'll need to click the "hand with arrows" button in the curves palette first).
That will put points on the R, G and B curves for that color (you won't see anything appearing on the composite curve).
Adjust the separate curves until the "known" color have the right values and hope everything else follows alright…

Then again, I'd guess doing it "by eye" would be just as easy…