Yeah the {dFb} rifle is customizable.  The UT3 one for the most part has pretty much all the config options that the 99 one has.

I'm not sure what your level is as far as programming but UnrealScript is the language.  It's based off of Java and VisualBasic and is heavily object oriented.

This is probably the website with the most pages on UnrealScript:

http://wiki.beyondunreal.com/

My main reference is this.  It's good for going through all the classes and knowing what methods/properties you can use.  It's a bit advanced but I'll give you the link just in case you want to take a look:

http://unreal.student.utwente.nl/uncodex-ut/overview.html

The tools I use are EditPlus, the command prompt (for ucc.exe) and WOTgreal Exporter (http://files.filefront.com/wotgrealExporterzip/;4264212;/fileinfo.html).  A lot of people use the WOTgreal editor- http://www.wotgreal.com/.

Here is the current config minus the per game part (dFb_UltraRifle59d.ini):

[dfb_UltraRifle59d.dfb_Ultra_Rifle_Ammo]
setMaxAmmo=999
setBoxAmmo=333

[dfb_UltraRifle59d.dfb_Ultra_Rifle]
setRifleDamage=45
setInitialAmmo=500
setStillFireRate=6
setMovingFireRate=2
bMovingAccuracy=True
bStillAccuracy=True
setHeadshotBonus=3
bAlwaysHeadshot=False
bMomentumInJail=True
bNoHeadhot=False
setZoomMax=45
setZoomTick=3
setZoomTimer=0.2
setZoomChangeScale=0
setZoomChangeEver=0
bUseSmoothZoom=True
setBulletMomentum=0
bToasty=False

[dfb_UltraRifle59d.dfb_UltraRifle59d]
bArena=False
bGunEnabled=True
bJustRemove=False
bUsePureFix=False
bReplaceShockRifle=True
bReplaceChainsaw=True
bReplaceUT_BioRifle=True
bReplacePulseGun=True
bReplaceRipper=True
bReplaceMinigun2=True
bReplaceUT_Eightball=True
bReplaceUT_FlakCannon=True
bReplaceEnforcer=True
bReplaceImpactHammer=True
bReplaceRedeemer=False
setGoreLevel=0
bReplaceTranslocator=False
bHitsounds=True
bStartWithRifle=True