In order to conserve internal memory space (10 MB) , I tried the following:

mkdir /media/mmc2/usr_lib
cp /usr/lib/libwebkit-1.0.so.1.0.0 /media/mmc2/usr_lib
remove /usr/lib/libwebkit-1.0.so.1.0.0
ln -s /media/mmc2/usr_lib/libwebkit-1.0.so.1.0.0 libwebkit-1.0.so.1.0.0
the symlink exists (I tested)

But the browser did not start properly in webkit mode.
Why ? For the OS a symlink is the same as a 'real' file ?