The best suggestion I can offer in light of the fact that you have 7.3.4 is to modify your startup script so that it does a 'startup open restrict' instead of a standard startup - thus only allowing users with the RESTRICTED_SESSION system privilege to connect (typically, this will only be the DBA users).

Then the script could run your SQL script, and finally issue the SQL command 'alter system disable restricted session' to allow the normal database users to connect.

HTH

David.