That's actually quite easy to do. All you need is to make a Dummy Building which gives the Production Bonus and assign it into the trait via FreeBuilding.

Make a Dummy Building just like you would make a Building normally (including a Buildingclass, Text and Description Even If it's just "TF Dummy" as an example) but set the Cost to -1 (unbuildable), FaithCost to -1 (Same reason), PrereqTech to NULL (to hide it from the Tech Tree), NukeImmune and NeverCapture to true. If you want, hide the Building by Setting the GreatWorkCount in -1.

For the Military Production boost, Look at the Forge and Seaport in the Buildings.xml file. Hopefully, the effect's obvious to discover.

You can add me to Steam or Civfanatics If you like, but I might not reply immediately, as I'm currently making a Civ for myself. But you can Message me in case of questions or help.

If you want to make TF2 Civs I do actually have a few in mind that you can do but I think you need to make unique buildings and units for each class. Here's some ideas I have

Scout
UA:Force-a-nature
All Units are not effected by terrain and gain a +1 movement

UB:Bonk Facility
Replaces Armory,
-3x Cost of normal armory
-No XP given
+All units made in the city have a chance to evade melee attacks

OR

UB:Intel Collection center
Replaces Constabulary
+All spies take x2 as long to take intel in city
OR
Replaces National Intelligence Agency
+Spies steal intel 50% faster

UU:Primitive Scout(EDITED)
Replaces Warrior
+Can Escape Melee Attacks
+Not affected by terrain(Hills,Forests etc.)

Soldier
UA:Shock and Awe
All units recieve +15XP from the start & all tourism taken and given is halved

UU:Direct Hit Soldiers
Replaces Bazooka
+Recieves 80 Air Interception

UB:Rocket Jump Training Center
Replaces Military Academy
+Gain Resistance vs. Air Units

NEW IDEAS

Spy
(All in a Day's Work)
UA:Recieves 1 Extra spy upon espionage being enabled, All spies steal techs 1.5x faster

UU:Spy Ring(Replaces GW Infantry or AA Gun)
+Recieves 50% bonus vs. Siege Engines & 25% bonus vs. Cities
+x2 Flanking Bonus
+May Move after attacking
-Reduced Overall Combat Strength

UB:Spy-Checking Center(Constabulary or Police Station)
+x2 chance of catching enemy spies in the City
-Costs Extra Production

Medic
(Oktoberfest)
UA: During a golden age All units heal x2 as fast & cities grow 1.2x faster

UU: Crossbow Medic Squad(Replaces Crossbow)
+Recieves Medic II when first made
+Can double as melee units
-Ranged Strength is lowered

UB: Medical Lab(Replaces Hospital)
+Provides +20% Science Boost in City
+1/2 Maintenence
-Provides only +3 instead of +5 Food

Engineer
(Use more gun)
UA:Units that fortify start at half fortification bonus(20%) but after 3 turns gain a 60% defense boost, Forts and defense buildings are built in half time and cost

UU: Sentry squad(Replaces Machine gunor bazooka)
-Requires 1 turn to setup
+Range strength is increased
+Enemies take damage when ending their turn next to this unit
+Increased strength when defending a city

UB: Engineer's Workshop(Replaces Workshop)
+Every era after increases the production bonus by 5%
+10% Bonus to constructing industrial era+ units
-Increased Maintenance cost

Sniper
(Bushmen's Rules)
UA:+All ranged damage dealt is increased by 20% and XP from ranged attacks are doubled

UU: Sniper Riflemen (Replaces Riflemen)
+Can double as a two tile ranged unit
+Can move after shooting but not attacking
-Has a penalty on defense vs melee

UB: Rifle tower (Replaces Castle)
+The city its built in can see farther than normal
+All Gunpowder or Ranged units built in city recieve +10XP

Hey TMaster, I threw In a few more ideas that are possible see what you can do with them

I would love to see a TF2 civ which incorporates all the mercs in it :)

Originally posted by Sankyo8:

I would love to see a TF2 civ which incorporates all the mercs in it :)

Would It sound like this?

Mann Co Civ(We Sell guns and get in fights)
-City-States that you have a trade route with gets additional Defense and you recieve units every few turns, regardless or whether militaristic or not
-All units gains 1.5x more XP when fighting in friendly territory

Mann Co Store(Replaces Market/Bank)
+Gives a small 15% Culture modifier to the city(The Hats)
+Gains an additional +2 GPT when a Golden Age is active(Steam Sales)
+Gives Gunpowder Units +15XP when made in the city(The fact they lend weapons for a week)

Mercenaries(Replaces GW Infantry OR Infantry)
+Has a variety of unique promotions
+ 25% Bonus vs. Armor(Fought robots for a while and have explosives)
+1 Sight (Sniper, Spy and Scout make good recon units)
+ Has a weaker 1-tile ranged attack of 28 or 40 (Snipers, Spies, and Scout Harassment)
+ Has 60 Interception (Miniguns, Airshots, Rocketjumps)
-Overall Weaker, 45 vs 50 or 63 vs 70(No Matter how you put it, 9 Crazed Mercs don't serve as well as 10+ orderly Riflemen)
- Is more expensive costwise (400 vs. 320 OR 450 vs. 375)

Something like that, that does sound very interesting though!

One of them should has scouts the are power full in damage