You can't without looking for some LISP commands which would probably extract it for you. Best go to the likes of TheSwamp, CADtutor or the AUGI/Autodesk forums to hunt for that.
The easiest way is changing the linetype of the layer the object is setting on, or selecting all the objects with that linetype assigned and manually overriding it's properties.
If you need just to change the scale of the linetype, select the object and adjust its linetype scale value (CEltscale) in the Properties tab.