welcome to BeoWorld.
Yes, it can be done - and there are actually lots of these kinds of discussions in the forums.
I know that I have interfaced my 6000s to line out signals.
A check of the 8000 manual should tell you if they only take powerlink or they, like the 6000, have the additional line out/in connection.
(I think there was a recent conversation in this area about the BeoLab 2)
The challenges will be:
-- if the audio signal goes quite the speakers will think the system has powered off and so they power off, and then power back on when the volume is resumed ... can lead to *pop* sounds and the loss of a note or three
-- volume control, this will depend on the TV or its amplifier
There will be others who can give you specific advice on cables, etc
First B&O (1976) was a Beogram 1500 ... latest (2011) change has been to couple the BL11 with the BL6Ks *sounds superb*