Installation of Adobe Creative Suite 6 hangs at AdobeHelp on Mac OS X El Capitan
Here is a workaround for this issue:


Restart the system, as the installer had to be force quit, and could not be relaunched easily.
Mount the ProductionPremium_CS6_LS7.dmg disk image. (Or I assume any of the other CS6 products)
In Finder navigate to CS6 ProdPrm, then Adobe CS6 Production Premium, then payloads, then AdobeHelp, and execute Adobe Air Install.app.
Once the previous step is complete navigate to CS6 ProdPrm, then Adobe CS6 Production Premium, then payloads, then AdobeHelp, and execute AdobeHelp.air.

Note: As Karl pointed out, the AIR installer bundled with certain CS6 products may not install on Mac OS X El Capitan. If this is the case, you will need to navigate to https://get.adobe.com/air/ and and download and install Adobe AIR.
Once the previous step is complete navigate to CS6 ProdPrm, then Adobe CS6 Production Premium, and run Install.app.