With a working database running with UTF-8 as the default character set, it becomes a simple matter to convert select columns to univarchar:
% isql -Usa -P > use xpubs > go > alter table authors modify au_lname univarchar(255), au_fname univarchar(255) > go
The columns will be modified to the new datatypes, the data will be converted in place, and the index will be re-created.
