If anyone is interested, I made this work in 1.5.
Step 1:
Download and install mod as normal.
Step 2:
Go to '...\Mods\StellarDiv\Game' and delete these files:
MapSetupDefs.xml
MapSizeDefs.xml
PlanetArtDefs.xml
Step 3:
Open 'StarDefs.xml' and paste in the following:
<Star>
<InternalName>SnathosStar</InternalName>
<DisplayName>SnathosName</DisplayName>
<ObjectType>Star</ObjectType>
<Type>YellowStar</Type>
<ArtDefine>SunArt</ArtDefine>
<SFXDefine>STAR_AMBIENT</SFXDefine>
</Star>
Step 4:
Open 'StarSystemDefs.xml' and paste the following:
<StarSystem>
<InternalName>SnathiSystem</InternalName>
<DisplayName>SnathiSystem_Name</DisplayName>
<Description>SnathiSystem_Dec</Description>
<OrbitLane>
<LaneType>Star</LaneType>
<Body>
<BodyType>UnaryStar</BodyType>
<BodyDef>SnathosStar</BodyDef>
</Body>
</OrbitLane>
<OrbitLane>
<LaneType>DeadZone</LaneType>
<Body>
<BodyType>Planet</BodyType>
<BodyDef>PlanetPebble</BodyDef>
<Position>0</Position>
</Body>
</OrbitLane>
<OrbitLane>
<LaneType>HabitableZone</LaneType>
<Body>
<BodyType>Planet</BodyType>
<BodyDef>SnathiPrime</BodyDef>
<IsHomeworld>true</IsHomeworld>
<Position>5</Position>
</Body>
</OrbitLane>
<OrbitLane>
<LaneType>NoRandom</LaneType>
<Body>
<BodyType>Asteroid</BodyType>
<BodyDef>NormalAsteroid</BodyDef>
<Position>2</Position>
</Body>
<Body>
<BodyType>Asteroid</BodyType>
<BodyDef>NormalAsteroid</BodyDef>
<Position>11</Position>
</Body>
<Body>
<BodyType>Planet</BodyType>
<BodyDef>PlanetAcorn</BodyDef>
<Position>17</Position>
</Body>
</OrbitLane>
</StarSystem>
Step 5: Hopefully enjoy the game and this great mod.
I've tried with and without other mods and it seems to work just fine. Even works in the map editor.
For sanity's sake, I pasted the above lines where they go in the vanilla files, between Thalis System and Minor System.
P.S. - I love this mod. Please don't let it die!