I have done many upload of information from Access to Oracle NOT with a pl/sql stored procedure.
Simply configure an ODBC connection to your Oracle DB.
Open you Access database and create linked tables (only the one you want to populate)
Write some sql (insert/update) statement against these linked tables.
Then your data will be on you Oracle DB.
Solution 2: (should be easy to build, but I have never done it)
Write a java stored procedure that will connect to your Access db and your Oracle database using the the jdbcdbc bridge, then publish it in pl/sql and the trick will be done as well...