Yes.  Just as you could write Web-Pages you saved manually 
to CD.

Select the folder(s) with the site(s) you want and write 
the Data to CD (with Nero, EasyCD or other CD-authoring 
software).  The site should be as functional off the CD as 
it was on the hard-drive (all links are relative and saved 
in the same HTML or other format used on-line) 

Make sure you use Options>>Build>>ISO9660 option on File-
Names in HTTrack.  If you already downloaded without that 
option, make a back-up copy of the mirror, select ISO9660 
option and select "Continue an interrupted mirror".  If you 
don't want to "Continue interrupted mirror", you could just 
Zip the directory and write the small-filename zip to CD.   

If you don't want the CD version to link to sites online 
also select  Options>>Build>>No external pages.  

If you aren't interested in updating the mirrored site 
later you can delete the hts-cache directory.