Ahh yes, the infamous "Armageddon mission of Doom", where Wing Commander Saga's mission design fall at the seams. The really frustrating thing is that there are no special tricks or tactics that make the mission go smoothly, so there's a big part of luck in it, namely that your "attack any enemy"-ordered wingmen will actually target some of the bombers.
So really the only things that I can suggest are :
- Turning down the difficulty as much as you are comfortable with - it will increase the bomber's lock time, and thus make things slightly more fair.
- Load up dumbfire missiles if you aren't already - a single missile should one-shot (or nearly one-shot) a bomber.
- Since you'll need to jump all over the place for the duration of the mission, make sure to use the afterburn-glide trick in order to avoid running out of fuel - that is, make a short afterburn to get to max speed, then toggle glide and coast to your target.