The problem is not a technical one, resolving this would need to add one line of code in the class org.apache.torque.engine.platform.PlatformMysqlImpl in the method initialize():
setSchemaDomainMapping(new Domain(SchemaType.TIMESTAMP, "DATETIME"));
The problem is rather a compatibility issue. The Torque team has tried hard not to make any hidden incompatible changes between 3.2 and the next release (which is probably called 3.3), and I'd consider this change to be such an incompatibility (people might rely on the magic behaviour of the timestamp).
My personal idea would be to address this issue in 4.0-dev. In the meantime, if you have problems with this, you can get the sources, make the change above, and recompile the Torque generator.