I'm not a tuner guy and usually don't reply to tuning posts but it is a holiday and nobody has posted yet so here goes
I was just looking at the IQ. Pretty cool! Music, movies, Microsoft Office documents, GPS, code scanner, gauges with alarms, logging, tuning....the list goes on. Banks makes some nice stuff but the general consensus around here is that there is a problem with the tuning files. It seems Banks has had some issues with trans tuning on the F250/6.0 trucks causing premature transmission problems.
As I understand it,(and I'm no expert) a tuner capable of changing tunes on the fly uses a different strategy to change the behavior of the engine/trans. Instead of overwriting the values in the trucks computer memory, it modifies the sensor readings and "tricks" it into behaving differently (more power, firmer shifts or whatever). While this can work on the engine ok, the changes to the computer controlled trans are coarse or large, not the fine smooth tuning possible when your directly changing the preprogrammed responses in the trucks computer. Banks tuners have been "tune on the fly" -including your 6Gun- and this can be hard on the trans.
Most of the trucks running tunes here have custom programming. A quick search here will bring up 3-4 sources for software that will consider things like what other mods you have on your truck and how you intend to use it. Most of these guys have a preferred platform as far as hardware.
A Y cable is available for OBDII but it depends on the devices if they will play nice together or not. Usually not. There are multiple data busses running at the same time and I suspect each one will only make one connection. If the devices are requesting communication to different busses they could work, otherwise the one that connects first will cause the second connection request to be ignored.
Things are changing all the time and My thinking may be out of date but I would contact one of the recommended tuner gurus and ask them about what hardware works best. Several options for tuners/monitors are available.
"Thinkin ain't knowin"
2006, King Ranch, F250, Lariat, Super Duty, Powerstroke, FX4, CC, SRW, 20in Ultra Motorsports Goliath wheels. 2in leveling kit, Husky 16K roller hitch, ScanGaugeII. Sinister coolant filter. Blue spring. BPD EGR cooler. Riffraff CAC boots w/metal cold side tube, STC update. Fumoto valves. Rotella ELC. DashBoss. '08 Mirrors. Mishimoto Rad and 200° stat. High Idle Mod. 3G Alt.