The big thing to keep in mind is that you really don't want Dominator to be surrounded, that's when it goes crazy.
It's awesome in a long range shootoff, and the best bodyguard cruiser you can have against big enemies (Radiant jumps a cruiser/low flux capital, Radiant cries as the Dominator unloads).
So main part of making it work is keeping it on a waypoint tucked close behind the big tanks, cruisers will spread out during the battle anyway:
If it doesn't get surrounded and can actually shoot its guns damage output will be very good, matters more than anything you could do with the loadout.
Have something fast ready to clean frigates that'd get behind your fleet, no ship likes being completely surrounded.
Loadout:
Skills:
Turreted railguns/maulers make sure it can always contribute and swat smaller things well, don't need that much PD on the front.
Reapers buffed to 7 ammo are great, do not need racks for them. Even with triple ordos and elite missile spec Dominator finishes the fights with 2-3 left in each mount.
If you want to tank with armor it'll need more skills and builtins than high tech. If you need to drop something bulkheads, rangefinder and RFC are the first 3 to go.
Least important skill is impact mitigation, it's a must if you want durability but all the others are needed for offense.
I have hull restoration so all my officers can skip combat endurance, ordnance expertise can be swapped for combat endurance if you don't get 100% CR otherwise.
Missile spec should be the first elite, ballistic 2nd if you have more.
Typical battle result against triple ordo (not piloting any ships, hopped in at the end to check leftover missile ammo):
Above average battle result: