Download firmware and FS, and download simlockpatchgen (you can find it if you search on 4shared), the correct custom pack for your mobile (don't know if XS++ has got custom files for w660 buillt in, if it does then just use that one), and SeTool Lite V1.11 (you can also find this on 4shared).
Now unzip the firmware and the fs, open simlock, and chose the main frmware, and press make patch. The patch will be stored in a folder called vkp inside the simlock folder.
Now open xs, connect the phone, and flash firmware, fs, and cda (custom pack).
Now close XS and open setool lite.
Choose the patch file you created with simlock under "misc" files, and press write script.
Now your phone shold be free to use any network.