Hi All-
Needed some guidance on a project I'm working on attempting to drive two actuonix pq12 actuators in tandem, with a L293D H Bridge.
I've verified the actuators work (with the LAC control board) however I've been using the RC signal connection to control them. I was wondering how to connect the LAC board to the H-Bridge, given that the RC signal is just one connection, whereas every L293d example I've seen uses the motor input and output for a standard DC motor set up.
here's the data sheet for the LAC board: https://s3.amazonaws.com/actuonix/Actuonix+LAC+Datasheet.pdf
Sorry, I don't understand what you want to do 
There seem to be actuators, a controller, an H bridge and (supposedly) an Arduino. Which of these do you want to connect how, and what's the role of the Arduino?
Each of the arduinos has to be wired to the LAC control board. I'm wondering how to set up the circuit so that both of the actuators can operate at the same time, using only one arduino.
The controllers have a couple of interfaces, analog and digital. The RC and PWM interface looks quite promising, it's easy to use and an Arduino supports multiple such connections. See "Control Modes" at the end of the LAC data sheet.
An H bridge is not required for a LAC connection. It can be useful in driving the actuators directly, without the LAC controller.