i used to have the x530... not a bad set of pc speakers for the money.
with that said, they require 3x3.5mm connections for surround sound to work for them which isnt support by home theater so you would need to convert this to a 6x rca which isolates each channel.
now you have two options for this.. if your tv supports 5.1 out of an optical output you can use that or you would need to patch into the hdmi cable from the source to extract the sound. the downside of the source is that if you have a smarttv and use its apps or are viewing local channels you will not get sound from the system. if your tv does not support 5.1 out of its optical then the best you could get is 2.0/2.1 (which you could get without an adapter if your tv has a headphone jack).
regardless what you're looking for is a box similar to
http://www.voelkner.de/products/698895/100-xl.jpg which is an audio extractor (they make them with hdmi inputs and optical inputs as well as ones which support hdmi output as well for passthrough) with 5.1 support. you would then need rca to stereo 3.5mm adapters. if the content is being broadcast over hdmi or optical in 5.1 it will convert it to analog and pass it along to such a speaker set.