It is normal behavior. When you shift without lifting the throttle, a huge amount of torque go to the wheel when you let the clutch out due to engine-transmission revs mismatch. Thus, it will make your wheels spin a little, and this is immediately handled by the traction control by cutting the throttle.
Start your car, just roll out at any speed you want. Then, turn off the ignition, put you in neutral, and wait for the engine to come to 0 RPM (it might take a while, be sure to have space in front of you).
Then, without touching any pedal, enter a gear. The gear will mesh, even if you don't press the clutch!
I'm using an H-shifter and I tested this on the LX6.
I can see a solution: if the driver engages a gear on its shifter, but doesn't depress the clutch, he would *have* to get out of the gear, then put it again (while clutching, this time...) for it to work.
Before, we couldn't go in neutral while the transmission was under load. It was realistic (at least for standard synchronized gearboxes, I think dogboxes can, not sure). But now, I can go to neutral while accelerating. (BTW, I use a H-shifter.)
I just tried it, and it works, however it's not _very_ realistic.
But for about 70 % of my "tests", it made my engine stall. Better than nothing!
To install it, just copy the DLL and the EXE in the LFS directory, edit cfg.txt to enable the OutGauge as said in the text file within the archive, then run Outgauge_Stalling.exe and run LFS.