I did it!
I want to share a method I found for creating a 6 channel separation without any special PS plugin or dedicated software, just MacOS X and PS CS.
First I separated the files from RGB Working Space to hexacrhome using AppleScript ColorSync scripts found on MacOS X. I edited a bit the scripts to automatically use the embed profile as source, then ask for the hexachrome profile and do the conversion using different rendering intents and best quality settings for Apple’s CMM. This results in a 6 channel TIFF, that al-thru it’s correct, basically no normal SW can open it. So, I managed to open the file forcing Photoshop to open it as “Photoshop RAW” (don’t confuse it with “Camera RAW”). You have to type the pixel dimensions of the file (which I know from the original file) and set 6 channels. Then, the file opens in negative as RGB plus 3 alpha channels, from this all you have to do is convert it to multi-channel, invert all, set the correct color definition for each channel and the correct sequence (you have to figure out what channel data corresponds to what color). I created a Photoshop action to automate the process. Finally, you have a multichannel document ready to be saved as Photoshop DCS, and that’s it!
I hope this to be useful to others. It saved me some money and as I said in a previous post, I regularly use ProfileMaker 5 plugins but some times I need to use profiles created with different software (e.g. Monaco) and this method resulted very fast (thanks Apple’s ColorSync CMM) and strait-forward after automatization.