While I've never done them, I see no reason why you couldn't create them, they would be difficult o do though as you would have to be very careful about how many different scenario's there are and therefore how many different permentations of code there could be as each of these must compile (Or it will fall over when you try to dynamically create the trigger)
First off do you really need dynamically created tables. Could you use a generic table with perminent triggers and just truncate it at the start and then use isert into select to populate it.
If the above won't work for you then Look up Native SQL (if your using 8i) or DBMS_SQL (if your on Oracle 7 or Native won't do it) on technet.oracle.com. Membership is free and you can search the Oracle Manuals online.