See: http://www.postgresql.org/docs/9.1/static/arrays.html
If your non-native driver still does not allow you to pass arrays, then you can:
pass a string representation of an array (which your stored procedure can then parse into an array -- see string_to_array)
CREATE FUNCTION my_method(TEXT) RETURNS VOID AS $$
DECLARE
ids INT[];
BEGIN
ids = string_to_array($1,',');
...
END $$ LANGUAGE plpgsql;
then
SELECT my_method(:1)
with :1 = '1,2,3,4'
rely on Postgres itself to cast from a string to an array
CREATE FUNCTION my_method(INT[]) RETURNS VOID AS $$
...
END $$ LANGUAGE plpgsql;
then
SELECT my_method('{1,2,3,4}')
choose not to use bind variables and issue an explicit command string with all parameters spelled out instead (make sure to validate or escape all parameters coming from outside to avoid SQL injection attacks.)
CREATE FUNCTION my_method(INT[]) RETURNS VOID AS $$
...
END $$ LANGUAGE plpgsql;
then
SELECT my_method(ARRAY [1,2,3,4])