screenrc and colors question

hey everyone,

I'm having a bit of a problem with configuring screen via
it's .screenrc file.   My question is with colors in the caption.
According to man screen: "Colors are coded either as a hexadecimal
number or two letters specifying the desired background and foreground
color (in  that  order)."

For two letter codes I have no problem, for instance:
caption always "%{RW}%t - %n"
shows the caption as bright red text on a bright white background.
My problem is with using hex numbers to specify background and
forground.   I'm not quite sure of the syntax.

For instance, what if I wanted blue text (hex #0021A5) on an orange
background (hex #FF4A00)...   I must be missing something really
simple here...