Unfortunately, you can't do this with the FDK. makeotf uses a lookup table from Windows code page number to OS/2 usCodePageRange[12], and will reject any values that are not listed in the OpenType spec OS/2 table specification.
You can do this by scripting with the 'ttx' tool, which dumps an XML version of the OS/2 table, and report the OS/2 usCodePageRange as a bit field. You can edit this field, and the merge the new definition back into the font 'ttx -m <path to font file> <path to ttx ML dump of the OS2 table>'.
The OTMaster tool from DTL also lets you edit this kind of stuff directly, from a UI. FontLab may als let you do this - have never tried.
- Read Roberts