There are some plugins for blender to import / export Supreme Commander SCM and SCA files. But unfortunately the process of getting from Total Annihilation's 3DO format to SCM, complete with textures and correctly placed, oriented and named bones, isn't straight forward (or at least I couldn't find an easy solution). So I put together a tool to help. I released it on github for others to use, maybe it can save you some hours. See https://github.com/Axle1975/3do2scm/releases/
Big shout outs to Michael Heasell for writing the Robot War Engine (https://github.com/MHeasell/rwe) and the many developers who worked on the Blender plugin itself (https://github.com/Oygron/SupCom_Import_Export_Blender). The 3do2scm converter makes heavy use of code from both of those fine projects.
For your porting pleasure, as of release 20200907, 3do2scm includes a tool to assist you convert TA animation scripts to SupCom SCA format.
As of release 20200911, 3do2scm is able to generate SpecTeam (team colour) textures, and now saves textures in .PNG format. The user interface to nbos2sca.exe is also simplified, allowing user to drag/drop nbos files onto the exe.