Everything stated here seems to not work anymore. Thanks ED!
While playing around with CTLD's jtac autolase function, I discovered that using laser code 1113 will show a diamond in the HUD of the Su-25T.
Further testing showed, that - if you manual override (left alt + w) - you actually can use the laser guidance to fire the Su-25T's laser missiles without having to lase them yourself. You just have to wait for the diamond to become a circle, press alt + w, fire and forget. Not only that, it also gives you a higher fire range for ALL of the missiles, so Kh-29L, the 25ML and the S-25L have the SAME firing range (which obviously seems to be a bug).
I have tested this successfully in the mission editor (SP), hosting a multiplayer myself and joining a MP game. It did not work with the Su-25, though. The Su-25 activates its own laser after you've fired the missile and even if you turn of your laser directly after the shot, the missiles would just explode somewhere in air.
It also does work when CA buddy is lasing.
A-10C is confirmed working (thanks Isegrim)
See the attached mission. Just start the mission, activate ground mode (7) select one of the missiles, press alt+w for manual override and wait for the rectangle to turn into a circle - FIRE!
The mission uses mist and CTLD for CTLD's jtac autolase feature. I did not test it with vanilla DCS as I don't know how to make a unit lase a target on a specific code.
Does anyone have more experience in this? su25t_laser_1113_test.miz