Dash Command doesn't (to my knowledge) have a transmission temp reader. So on my iPhone I used Engine Link, then used [MENTION=70922]Robb235[/MENTION]'s instructions from his thread (link below) to set up the trans temp.
http://www.toyota-4runner.org/1591876-post29.html
I ultimately decided to switch to a scangauge, but listed below are a few pros and cons I experienced with the iOS setup.
Pros:
1. Awesome display, including graphing out fuel economy and giving you much more than the standard four at a time of a scangauge.
2. If used with an old iphone and you also download an offline maps app (motionx, gaia, galileo, etc), you have a gps and scangauge in one unit.
3. No wires to route and zip tie to anything during setup. Granted, I didn't do this with my scangauge, but I know a lot of people prefer a cleaner install and I'll probably have to at some point as I'm sure that pesky cable will get on my nerves eventually.
4. An app like Engine Link has a "mirror" option for setting the device on your dash, which will then project a reflection onto your windshield, giving you a sort of poor man's heads up display. Not sure if it's a huge feature, but a cool little trick.
5. Easily removable to put into another person's rig and check on anything if you need/want to. If you unplug a scangauge, it resets itself and constantly setting up the trans temp can be a little bit of a pain.
Cons:
1. You have to reconnect the device to the obd dongle every time you start the truck. This can get very annoying and lead to me often just leaving my truck on while stopping on the trail, which I'm not a fan of doing.
2. I also experienced connection issues. Sometimes, when on a trail for an extended period of time, I noticed that it would still say I was going 20mph when stopped, or that my transmission was only around 180° when I had just been climbing rocks (I've mentioned in at least one other thread that my tranny gets pretty hot because I don't feel the 70264 was big enough to fight the AZ heat). This was due to the connection sometimes dropping out on the dongle and I would need to reconnect it to get accurate readings again.
3. The screen on an iPhone, iPad, etc. is very glossy. If the light hits it just right, you get a pretty pronounced glare and I wasn't the biggest fan of this. Granted, you could easily buy a matte-finish screen protector, but I never did because I was too lazy to do so. Someone with more initiative than myself could definitely rectify this minor problem.
4. Consider getting your device a lifeproof case or something similar if you're going to use it while out on the trail. Here in the desert, things get pretty dusty, but I would imagine in other regions you could have issues with mud, water, etc.
So your mileage can definitely vary with this, but those were my experiences. I didn't mind the iOS setup, but I wanted something a little more fixed in the truck that turned on every time I turned the truck on without any connection issues because I'm anal about watching temperatures and things like that. I'm sure that once I put in a bigger tranny cooler I won't worry about it as much and I'll watch it less, but I'll cross that road when I come to it.