for tray in and tray out there is a very easy solder point on the front circuit board,
look at the drive from the front, have it turned so you see the bottom of the pcb where the ribbon cable is soldered to it on right half,
now look towards the left side of the pcb, where the hole is that that little plastic piece hooks onto it and holds it down, there are two solder pads just to the left of that hole, below those two solder pads are two more, those are your tray ins and tray outs, use a multimeter to see which one is which by testing them to the ribbon cable,
You can also find eject i believe somewhere near the eject button on the front pcb too like i said just use a multimeter off the known pin on the ribbon cable for eject and start probing around till you find continuity.
I cant really tell you which ones are which because everytime i do it i just test it with a meter from the original points you guys broke off so im unsure exactly what pins on the ribbon cable belong to what.
and make sure you have the right two pads for the tray in and tray out...... on the multimeter you will get a reading on the other two pads near it because they are connected via resistors. so when your trying to find tray in and tray out make sure the readings are 0 or near it.