Boosting Ranged Touch Attacks

[PsyBomb]

Alright, this is going to be a bit vague since I'm working on it as a bit of a side project for now, but here it goes...

I am putting together a build that is going to be relying a lot on its ranged touch attacks. The problem with this is in execution, due to the circumstances of the EXTREMELY convoluted PrC chain I am using it's looking like his BAB is going to wind up in the 10-12 range. Other than Dexterity (which I'm not sure how much I'll be able to scrape together due to MAD), what other ways exist to boost Ranged Touch? This is unfortunately not a Ray, so I'm not sure if Weapon Focus will apply.

Pathfinder, with Dreamscarred Press, Drop Dead Studios, and Radiance House enabled by default.

[TiaC]

Compression or other size reducers can both boost your dex and give you a positive size modifier.

[Ninjaxenomorph]

Weapon Focus can always apply. Even if its some weird things. Morale bonuses from bards would do the trick, though that's less dependent on you and more their group.

[Extra Anchovies]

I'm assuming that your build loses a lot of BAB by dipping one or two levels in a lot of average BAB classes rather than taking one average BAB class for 20 levels. If that is the case, ask for fractional base bonuses (http://www.d20pfsrd.com/classes/unchained-classes#TOC-Fractional-Base-Bonuses).

Out of curiosity, what's the build?

[Psyren]

If you're using Combat Stamina (http://www.d20pfsrd.com/gamemastering/other-rules/stamina-and-combat-tricks-optional-rules), the base feat can let you add a +1 to +5 competence bonus to your attack rolls by spending stamina. The nice part is that you can choose to spend after you roll - so if you know that you hit on, say, a 14, you can hang onto your stamina for rolls 14+, choose to spend it on 9-13, and not bother on a roll 8 or lower. It also lets you unlock all kinds of goodies from your other combat feats that might help this build, such as letting Prone Shooter start counting for you the moment you drop prone and increasing its bonuses. A +6 untyped bonus to your AC should help you avoid any return fire.

[Mithril Leaf]

Permanent Alteration yourself down to Diminutive size.

My guess for the build basis is:
Riven Darts.