skiwillgee!!  hahaha..
i did do it thru the diffuse thing.. but used the sky preset thatw as there for the xray  mats...
but yup..i've realized too if you do change the angle of the camera..the blue is blue. my green becomes less transperent though and then becomes green to yellow to white to  nothing...leme see if i saved what i did or dumped it in disgust...
or I'll do a quick one and post it up