Install TMT 3, copy the file you need, and uninstall or use system restore. LAV Audio Decoder is the standard audio decoder with Red October and Red October High Quality on MC16. It will decode almost everything, including DTS-HD, but needs the dtsdecoderdll.dll file from your ArcSoft installation. Copy the file in the Windows\System32 folder for Windows 7 32-bit and the Windows\SysWOW64 folder for Windows 7 64-bit. I would recommend using the LAV Audio Decoder with the ArcSoft dts decoder file rather than using the whole ArcSoft decoder. It is simpler and you are assured of the best quality (correct channels, bitdepth, and sample rate).
If using Windows 7 64-bit, you also need to install msvcr70.dll and msvcp70.dll into the SysWOW64 folder. These files are only needed since you have TMT 3. I don't think these are needed for newer versions. You can get these from a Windows 7 32-bit installation, or google them and download.