I went through my collection and skimmed The Killing Fields, Shattered Sphere, and FM: Comstar. I couldn't find anything in Shattered Sphere. FM: Comstar mentions that the 12th Nova Cat Regulars conducted raiding operations on Cappelan held St.Ives worlds and lost a Trinary's worth of mechs doing so.
The Killing Fields gives a lot more detail. On pg. 242 mentions a battle between House Hiritsu mechs and House Daidachi armor against some St. Ives Lancers (1st?) and some Stars of Nova Cats at the Hildco mech factory near Tian-tan on St. Ives. Later in the book another battle takes place between the 1st St.Ives Lancers and 14th Donegal Guards (Adam Steiner's Unit :D) against House Hiritsu, House Daidachi, and the Taurian Jaegers. The Nova Cats were not mentioned in this latter battle on St. Ives.
This is all I got from a brief skim. With some more work I bet I could piece together a more complete picture of the battle for Tian-tan and maybe even find a few more mentioning of other Nova Cat forces.
Edit: Doh!! Of course Sarna would have all the information.
On St. Ives
Cappellans St. Ives
3rd Canopian Fusiliers Tau Galaxy
Concordat Jaegers Eridani Light Horse - 21st Striker
Pleiadas Hussars Aleisha's Mounted Fusiliers
Warrior House Hiritsu Raymond's Armored Infantry
Warrior House Daidachi 1st St. Ives Lancers
1st McCarrons Armored Cavalry 87th Comguard Division
Vong's Grenadiers (1 Bat) 14th Donegal Guards
Prefectorate Guard St. Ives Academy Training Group