i've generally assumed they were using LFB equipped jumpships so they could cross two systems at a time, and were doing a lot of "just barely not insane" hot-charging through uninhabited systems.
This is a reasonable assumption. They may have also jumped in a little close to the star to improve their hot-charging via sails.
and that the whole deployment doubled as an unspoken statement that had the clans not been a threat, the Fedsuns could have had the capability to strike deep inside the combine anytime they wanted without the combine seeing it coming.
Well, this capacity has always been in place because space is big; really big; vastly, hugely, mindbogglingly big. For every star that a Jumpship would normally go to in it's journeys, there are anywhere from 30-50 around that no Jumphip has seen in centuries.
The reason it isn't used is the same reason that we didn't drop the 10st airborne in to Berlin on D-Day: Having support when surrounded is important. Which leads to borders being used to provide said support. This becomes less a concern when you're not there to attack the owners, but to defend them.
command circuits aren't really a possibility here given that this is nominally hostile space (whole the clans had their attentions, and Theodore and Hanse made it clear during the Outreach conference that they would not be starting a new war while the bigger threat is present.. both sides were still technically in a state of hostilities. which means that you'd be sending those jumpships into harms way trying to set up a circuit.
plus, given the time it takes to move ships around, you'd need way more than the one month they had. plus you have to figure that any ships the fedsuns had were largely already being used to evac units from the clan front or conduct the minimum required trade to keep the economy afloat.
Getting the circuit in to the place is the hardest part for the whole thing. Arranging one to get one jump past the border isn't hard, it's the rest of the way.
Unless, as someone else has mentioned, there are some clandestine merchant marines who were just waiting for such an event to happen. Risky, though, as the ISF is always on the look out for such trouble-makers. But I doubt they'd be looking for the "Oh we're a secret command circuit from the Draconis March to Luthien who are set to move to uninhabited star systems all of a sudden to provide a sword path to the heart of the Dragon."
nor could they be using Combine recharge stations or arranging combine jumpships to move them, because their arrival at Luthien was a complete suprise to Theodore, and if they had been using a web of contacts in the combine, the ISF would have found out something was up.
Oh, that part isn't as hard as you think when the average dropship outguns the average jumpship, and then there are the marines they bring along to make sure they go to the right place. The hard part is using all those assets without anyone else finding out about it.
Of course, they could have had contacts in the underground forces to do just that. It wouldn't be the first time that the mafia had done something like this, especially if they also knew about the cats heading towards Luthien.
