Indexing varchar[]'s

If this has been asked and answered before, I am sorry.  I've been
digging through the mail archives and cannot find this particular
question (although some releated to int64[]'s).  Is it possible, with
7.1.2, to create an index on a varchar[]?

I've tried:
# create index foo on mytable (myfield);
ERROR:  DefineIndex: type _varchar has no default operator class
     and
# create index foo on mytable (myfield varchar_ops);
ERROR:  DefineIndex: opclass "varchar_ops" does not accept datatype
"_varchar"
     and
# create index foo on docket (case_name[1]);
ERROR:  parser: parse error at or near "["


Am I missing something obvious, or can it just not be done right now?

If it's not possible right now, is it in the works?  If not, could
someone point me in the right direction for creating operator classes,
or briefly outline what would be necessary to do this?

I'm new to postgres and have just starting looking seriously at the
sources.

thanks in advance.

eric