Bloodstorm Blade throwing an arrow and using Knock-Down?
Or likewise a Master Thrower with Trip Shot throwing the arrow, though taking weapon focus (arrow) seems like quite the waste. Perhaps as a Soulbow where the "arrow" is your mindblade.
In Pathfinder's Elves of Golarion, they have
arrows that trip, but they're not very good. Only a CMB of +5, and in PF CMB equals BAB + str bonus (or dex, in the case of a ranged attack) + size mod + all other attack buffs like inspire courage. So being hard-locked at +5 is pretty horrible. Not sure how it'd translate to 3E, but arguably it would have to remain sucky to be within the "spirit" of the original.
They're also expensive as hell;
25 gp per arrow.