If I read correctly the multiple manuals I've just downloaded, it seems you can input RGB from the tvonics into the system via the Scart on the Philips junction box, then upscale the image and output it via HDMI to the Panasonic projector, setting this in the HDMI menu of the general set-up on the Philips.
Unless, of course, anyone's actually used the thing and says I'm talking total balderdash!
If I am, then the only way seems to be to set the tvonics to output composite video via its Scart, and then use a Scart-to-composite lead to your projector.