I think that's the reason the OP decided to post here in this thread devoted to digital speech decoders...
DSD (referenced above but the link is broken, it should be DSD which is the original program can do it as well as the "new kid on the block" which is DSD+ (link for the download is found in the first post of that Reddit thread, there is no homepage or website for DSD+ at this time, might never be one).
Either of those can get you up and decoding as long as you're willing to do a discriminator tap but I'm not sure if the 396XT even supports that. You can't use the control channel output, it must be a proper discriminator tap or DSD/DSD+ won't be able to do much of anything with the output.
You can always get a $10-$20 "cheap USB TV tuner" aka an RTL stick and go from there, would be much easier if the 396XT doesn't support the tap - I think it's internal circuitry is so miniaturized that adding an actual tap is nearly impossible given the size of the board components but I can't say that for certain. I tried to find some info about a tap for the 396XT and didn't find much of anything so, it might be a dead end in that respect.
There are plenty of threads here in this subforum now that cover setting up RTL sticks using several different SDR applications such as SDR# (SDRSharp) being the most popular but there are others as well (SDR-Radio, HDSDR, SDR Ultra, etc), and plenty of info on setting up DSD and DSD+ too.
Browse around this subforum a bit, and read - really read a lot of the threads and posts because that's where all the info is.