Hell Will!

It depends on the module where you want to add this extension. For example - if you run this query in your UNA DB:

SELECT * FROM THE `sys_objects_storage` WHERE `object` = 'bx_albums_files'

you will find what extensions were listed in field `ext_allow`. So you need to change the value of this field to your own place by the same way.

With the best regards, Leonid