Yep! The Blonder Tongue modulators work very well! There are many threads on this website discussing set-up legality ect. here is one to get you started:
http://www.videokarma.org/showthread...blonder+tounge
Various models (pulled from CATV service) show up on eBay all the time.
add eBay example:
http://cgi.ebay.com/BLONDER-TONGUE-A...item230dbbff8f
not affiliated,
jr