Converting to 4-bit indexed .bmp in CS3?

I'm working on a project in which certain files have to be imported in indexed 4-bit .bmp format (gaming mod). In CS3, there is no option to save as or export in this format. After a bit of searching, there seems to be an issue with this but the posts are several years old. Is there a workaround available without having to revert to an older version of PS?

"You can specify either Windows or OS/2® format and a bit depth for the image. For 4-bit and 8-bit images using Windows format, you can also specify RLE compression". Straight from the Help files in CS2 but please remember that you have to change the image to grayscale first.