All of the information on Magash and the Troopers is useless unless it can be used in a gaming background. The Troopers are designed as a highly disciplined, very well equipped, mercenary force. They can provide an adversary for the PC's or can be used as a PC patron.
As a patron, Silvan's Troopers can hire the PC's as technical experts to assist in a mission, or as training cadre to train Troopers in specific new skills. The PC's can attempt to join as recruits. This would be best for a group made up of Diisarirgans. A group of PC veterans who left Magash decades ago can meet in the recruiting office, as opposed to the more common starport bar. The characters can be designed using the standard ex-military templates (for GURPS) or run through the standard character creation method for other forms of Traveller. They can then set out on the very difficult adventure of actually surviving training! (Anyone who doesn't think this would make an interesting game has never had to survive boot camp.) In GURPS then round out the characters with additional skills to match the Trooper template or Officer Template. A higher point count is justified because the Troopers are elite troops. The PC's will also pick up several disadvantages due to their enlistment in the Troopers. At the end the higher power PC's can begin careers as mercenaries in this elite company.
An alternative is to start the game as a Trooper detachment aboard a Broadsword or Kalashnikov Mercenary Cruiser. A PC group can fill all of the major command positions with NPC's filling the Trooper rolls. In this case the PC's would be on a rather long leash, though they may occasionally be called upon to perform specific missions for the Duchess. Typically they would be given a specific contract and allowed to fulfill that contract however they see fit. Rewards would be commensurate with success. The PC's would have access to really big toys, with enemies likewise equipped, for those who like that kind of game.
As an adversary the Troopers would be quite formidable. A boarding action, defending against Silvan's Troopers in ACA armed with cutlass, ACAW and Boarding Axe, would be a challenge for even the most high powered PC group.
The Troopers can also provide a relief for the beleaguered Imperial Marines, who often have to bail out clueless PC's who get in way over their head; and if the Duchess is with them the PC's might end up owing a powerful Imperial Noble quite a big favor.
Conversely the Duchess might hire the PC's to do her a favor which the Troopers, elite and powerful as they are, cannot accomplish. In which case the Troopers might be just window dressing, or the cavalry when the PC's have accomplished the mission.