By the nature of QScript, it has been designed to be a appframework interface. It means that anything in the game can use it.
If you want to use QScript in your own dll, first you have to connect to it.
Use the CreateInterfaceFn function with the QSCRIPT_INTERFACE_VERSION parameter which will return a (IQScript*).
Remember to check for null values!
qscript = (IQScript*)appSystemFactory(QSCRIPT_INTERFACE_VERSION, NULL)
(appSystemFactory is a CreateInterfaceFn you get in the Init or Connect function of a DLL class)
The interfaces work the same way.