The program gen_ctype_from_glibc.c will generate data files which can be
used by uClibc ctype functions to support locales.  From the comments:

/*
 * Generator locale ctype tables
 * You must have already setuped locale for worked libc (libc5 or glibc)
 *
 * This programm scan /usr/share/locale directories and write
 * ./LOCALE/LC_CTYPE files for system with uclibc
 *
 * Written by Vladimir Oleynik <vodz@usa.net> 2001
 * Base on ideas Nickolay Saukh  <nms@ussr.EU.net>
 *
 */


Sample usage to dump all the data files in a tmp directory:

gcc gen_ctype_from_glibc.c -o gen_ctype_from_glibc

mkdir tmp
cd tmp
../gen_ctype_from_glibc -d /usr/share/locale -c

Then just move the directory or directories you need (not the .c files)
to the uClibc locale file directory you set in Config.