well the topic pretty much says it all, i am looking for an easy way to do this lossless conversion without losing bit depth etc.
I am specifically looking for a guide if the process isnt simple gui newb proof.
AFAIK the simplest you will get is eac3to plus a GUI for it. There are several GUIs. Maybe ClownBD is one of the easier to use, but I don't use it myself and I have no reason to convert to flac anymore (cause there are decoders for DTS-HD and THD now) so I stopped doing that a long time ago.
For DTS-HD you will need to have Arcsoft TotalMedia Theatre installed though.