There is a standard IEC PC-like power connector, no need for custom cables.
Fortunatelly, CDTV has all types of video connectors: RF, Composite and RGB.
The best quality can be achieved using RGB connector. It is possible to connect it to SCART or VGA inputs.
For VGA you have to use a monitor that supports 15 kHz horizontal sync.
On the Internet there are suggestions to build a direct RGB-VGA pin-to-pin converter. I have not tried that.
Instead I purchased a commercial adapter. It included a 7408 chip, most probably to adjust the HSYNC and VSYNC voltage levels to TTL standard.