Custom colors in Excel with POI XSSF

I'm being asked to add some color to my RPG generated spreadsheets that call the POI Java tools to generate spreadsheets. I know how to specify some colors, using the HSSF tools that Scott Klement wrote, but, those are pre-selected colors and they're pretty horrid for things like creating alternate row colors. I need a much more muted palette.

Does anyone have an example where they have perhaps specified the RGB values of a color. If you do send an example, please also include any special prototypes you had to create to make it happen.

Thank you.


P.S.
Here is an example of what I'm doing now with the preselected colors:

RowColor(2)=COLOR_GREY_25;
RowColor(3)=COLOR_PALE_BLUE;

// Regular number
for idx1=1 to MaxColors;
RegNum(idx1) = SSWorkbook_createCellStyle(book);
SSCellStyle_setFont(RegNum(idx1): RegFont);
SSCellStyle_setAlignment(RegNum(idx1): ALIGN_RIGHT);
callp $SetColor(RegNum(idx1):RowColor(idx1));
endfor;

//**************************************************************
dcl-proc $SetColor;
//**************************************************************
dcl-pi *n;
inStyle like(ssCellStyle);
Index int(5) const;
end-pi;

//************
if Index<>0;
ssCellStyle_setFillForegroundColor(inStyle: Index);
ssCellStyle_setFillPattern(inStyle: SS_PATTERN_SOLID_FOREGROUND);
endif;

return;
end-proc;