Alternatively,

Stop LimeWire
Go into the directory where you installed LimeWire, look for a file called: limewire.props

Open this in NotePad and look for this line:
DIRECTORIES_TO_SEARCH_FOR_FILES=C\:<your_directory _here>

...and edit it to the directory of your choice.
make sure word-wrap is turned off before you save
Restart LimeWire and verify that it is sharing as you wish

Regards,
-T