Or upgrade your server to 8.x and use dollar quoting.
with dollar quoting all that is a thing of the past.
CREATE FUNCTION sp_slide_create(int4) RETURNS int4 AS
$$
DECLARE
aScriptID ALIAS FOR $1;
seqID int4 := nextval('genseq'); -- no magic needed with dollar qouting :-)
BEGIN
INSERT INTO tblslides (slideid) VALUES (seqID);
RETURN seqID;
END;
$$
LANGUAGE 'plpgsql' VOLATILE