I have http://maplantis.mikelat.com/index.php?mod=106
I want to replace the hero dark templar with that. I don't want to replace the standard dark templar. The way I understand it I have to edit the images.dat reference to point the hero dark templar to an unused GRP, such as ion.grp, and then call the lancer grp ion.grp and import to units\neutral\
Then I change the ion cannon iscript to be the same as the dark templar iscript. However, in game you can't see the hero dark templar or zeratul and after a few seconds the game freezes.

I'd settle for simply replacing the dark templar grp with the lancer grp, by renaming to dtemplar.grp and placing in either units\protoss\ or protoss\ (tried both and neither worked). Halp.

Not all of your .dat reference pointers are pointed correctly. Make sure nothing else is using ion.grp and make sure your new script uses the ion headers, because to my knowledge you need to use proper headers for it to work properly.

Bad news: You have to edit the WHOLE iscript, not just telling it what GRP to use, because your GRP can have many frames and SC needs to know what frame is used for what animation. I don't know much about frames myself, so you might need to ask Mesk

If the game freezes or something, that's definitely an iscript problem. You'll have to edit the Ion cannon's iscript to make sure that it has the same amount of frames as the dark templar. But I don't know how to do that. Iscript doesn't make any sense. :3

No, you're saying it wrong. This has nothing to do with the ion cannon (as long as Jack doesn't place one in his maps). I think the problem might be because dark templar's GRP has a few frames that the lancer GRP doesn't have, and when the hero dark templar tries to do an action that results in an animation involving frames that the lancer grp doesn't even have, and crash

Right. I got it mixed up. It's the dark templar that has to have its frames adjusted to work with the lancer.

The correct path is unit\neutral\ not units\.

If you do that and change the images.dat pointer to point at the DT's iscript, it should work fine, they have the same number of frames.

I had copied the DT iscript exactly into the ion cannon iscript, replacing it entirely. Would that not be the right way to do it?

Um, no. You just duplicated the DT into the ion's cannon's slot.

How bout you do as Voy said and check if both your lancer GRP is located at and your DT hero unit is linked to unit\neutral instead of units\neutral.

OK I got it to work. Now the firebat graphic is lancer.grp (renamed of course) and I can have both the standard DT and a lancer zeratul. Of course, the firebats are both lancers as well, but that's fine.

Huh. So you have two variety of lancers: One melees and bursts into the protossflamethingy when they die, while one conjures flames and explodes on death.

As a side note, you should test a firebat and do everything with it for a while to see if there is any problem. It would most likely crash when the firebat does the turning around that all terran infantries do while idle.

No, both firebats AND zeratul act exactly the same. They both use protoss flamethingy when they die and attack normally. Just zeratul is cloaked.