No. The 245 doesn't have a microphone input. Besides, the speakers for a home surround sound system are a bit too delicate for the distortion levels generated by karaoke.
Here's a $300 speaker (yes, $300 for a single speaker) wrecked from teens doing karaoke. They then bust it more messing around trying to push the tweeter cone together so the crack wouldn't be so noticeable
If you still want to go ahead with the idea then you'll need some other bits of gear. For simplicity sake I'd recommend a karaoke CD+G player. It will have mic inputs, vocal echo, and take care of putting the works up on screen.
The alternative is a mixer with effects (echo, reverb) - Cheap is Behringer Xenyx 1202FX
and a source device for music and graphics. This could be your PC, but you'll then need to go trawling for karaoke files and you'll need some software to play them and do the words. Sax & Dotty is pretty good software.
The PC sound needs to be connected to the mixer in a stereo channel. The mic goes in mono on a mic channel. The output of the mixer goes to the AVR on an AUX input.
Behringer XENYX 1202FX