MyBB merge script doesn't work with PostgreSQL

There are several SQL syntax errors preventing it from running on a postgres server. In addition, if it alters a table to add columns and there are no columns to add, it'll try executing "ALTER TABLE mybb_users" -- eg no extra code. It should instead do an isempty check.
Despite doing all of this in my modification of the script, there are still several errors in the script htat prevent it from working properly with PgSQL.
We are porting from a MySQL forum to PG, if it is important.