how to execute a package in my schema context

Hi,

I've written a package that works with a special set of tables I'm using in different schemas (i.e. MY_WORK).
Now I'd like to create it in a special schema (i.e. SERVICE) to avoid the redundance.
But executing it in MY_WORK it tries to modify the tables in SERVICE. It is so by design, I understand it. Normal usage of packages requires it in that way.
But is there a possibility to share the funcionality of a package for the same tables in different schemas.

-- 
Thanks
Norbert