+1 for having the input sensors on VT310 supported.
Maybe the outputs and GPRS commands too? 
The protocol is very well documented, PDF at:
http://www.meitrack.net/support/protocols
The good thing is if you implement the support for one model, you support all of meitrack's models.
(we are thinking of using other models, very satisfied with VT310)
Edit:
My bad, I just was not using the thing right. Looks like the IN1 and IN2 work, at least. will test the others 
Edit2:
Now I can read inputs 1 to 5, happy!
But like anibalfv reported for the heading change "alert", wialon does not accept the packet when the inputs are activated, only when they are reported by the timed interval. This is what I see in MyCOM:
Interval, with INPUT1 activated:
$$ }5 1 I U195006.000,V,2231.4673,S,04406.9321,W,0.00,0,070711,,*1F|0.0|357|0100|000E,000B|02D40002007C8E8B|07|000002FC
Alarm, *when* INPUT1 is activated:
$$ ~5 1 I 195201.000,V,2231.4673,S,04406.9321,W,0.00,0,070711,,*1A|0.0|357|0100|000E,000B|02D40002007C8E8B|07|000002FCA
anibalfv, did you solded your problem with the manufacturer? Any good news? I think this is the same problem, but I am not as good in "decrypting" this protocol as you guys 
If any other copy/paste or testing needed just ask!