I've done this hack on two of my CDTVs (I sold one).
I would suggest you go for the 'pro' type socket, as it makes the job a bit easier. At the same time, I added two toggle switches. The first one allows me to switch between CDTV boot ROMs and standard 1.3 ROM. The other one allows me to switch between PAL and NTSC modes (I think this switch had to be 3PDT On-On switch).
The CDTV has both PAL and NTSC oscillators built-in, so with this switch you get true PAL or true NTSC system. Of course, this works only with RGB monitor that supports these modes. Your CDTV RF card or your Genlock only work in the mode they were designed for.
Here is a photo of the connectors and switches on the back of CDTV.
http://mywebpages.comcast.net/dadica/ebay/cdtv3.jpg"
The other two photos show CDTV booting natively and with Kickstart1.3.
http://mywebpages.comcast.net/dadica/ebay/cdtv4.JPG"
http://mywebpages.comcast.net/dadica/ebay/cdtv5.JPG"
