Hi Winny,
It really depends on how complicated your current system is. I have worked on converting ColdFusion systems to PHP content management systems before. In my experience the most cost effective way to do this is to rewrite your code from scratch.
Although Jade is right, you could probably write a coldfusion interpreter in the OpenACS templating language, I think that Coldfusion is significantly complicated that this would be more expensive then writing your program from scratch.
Thanks,
Alex
