load library from different module in HVMC

[eluser]scibuff[/eluser]
Hello, I have the following structure

Code:

/application
/application/modules/common/libraries/vo/vo_abstract
/application/modules/test/libraries/vo/my_vo

and I want my_vo to extends vo_abstract

what is the proper way to "include" vo_abstract inside the my_vo code. I definitely don't wanna do something like

Code:

include_once( APP_PATH.'modules/common/libraries/vo/vo_abstract.php' );

because the "modules" path may need to change. Can I somehow autoload ("include") the vo_abstract in CI (without instantiating it, as it is abstract)

Basically, what I'm after is how can one library in HMVC extend another library from a different module in the HMVC?

thank you.