In which version of BL are you?
We have version 8.0
First of all TARGET properties reference only to servers. But you've a way to use properties from component.
If you want to use value of property coming from a component, you need to create a local property with the same name in you BL package and use this local property in the right place where you want the value coming from the component.
Then when you create your deploy job, on the instantiation of the property (Package tab), you need to change the assignment type to "Auto Map Component Property Name" rather than value as shown in following screenshot:
Hope this help.
This is exactly what I was looking for.