Phil,

Keep in mind that CGD is most commonly olefin.  Olefin has the lowest melting point of all the synthetic carpet fibers.  They are LUCKY that the holt melt glue did not melt the face fibers to start with.  I personally think your best bet is if it is at all brittle to use a scraper and remove what you can dry and then leave it alone.  You MAY find that over time foot traffic will remove more of it as well.

You have a higher probability of doing more harm then good on this one if you break out the heat and the chemicals.  So basically what Rick sad.