The templates file is a symlink to a file that exists within the tcz extension, which is read only.
Off hand, there are two options come to my sleep deprived mind:
1) Create your own "config" module that overwrites that file
2) Copy the real file (Probably /tmp/tcloop/wicd/etc/wicd/encryption/templates) over to replace the symlink, then edit /etc/wicd/encryption/templates, and make sure to add it to your .filetool.lst