A split/merge tool that breaks up and combines channels for Second Life files is available at
http://www.daylongraphics.com/products/leveller/download/secondliferaw.zipEventually a Second Life exporter will be added to Lev 2.6, but for now this tool lets one extract 8-bit raw files (one per channel) from an SL file, edit them, and then later recombine the files back into an SL file.
Ray