Well, for starters there is no pgsql SET type...
I use the varbit type that is present (but undocumented) in 7.0.3, but is fully supported (and slightly different) in 7.1
I wrote a function that converts an array of tokens into a binary string (1000100111) that I then insert into the database.
7.0.3:
insert into table VALUES ('b1000100111');
7.1 (SQL99):
insert into table VALUES (B'1000100111');
Chris