Okay. I get you've modelled your door as you want, Now the first thing to do is place The axis in the correct coords
Select your models, go to the hierarchy tab:
With your models selected, click on Affect Pivot only and place your axis At the bottom, at the corner where the hinges would be, like in this picture. i suggest you placing it a bit under the bottom, so there is no problem for the door to slide, because it wont hit the floor.
When you finished placing the axis, move to the door to 0,0,0 (not the axis, remember) and the grid should be showing for you the same as for me in the above picture. Remember to reset xform for scale and also to keep rotation on 0,0,0. You're finished, export your DFF (no matter if it has normals, vertex colours...)
Okay, now we go for the col, one of the interesting parts of this.
Make a box of the same size as the door, in the same place. now create some spheres in these places. think that the spheres will be what player will hit so he pulls the door, so its ok to have them bigger than the door:
remember to keep the boxes as boxes, and the spheres as spheres. Don't convert them to editable polies/meshes or you will have to do some fixes in COL editor.
Now select the box and the spheres, open Kam's COL IO and export your COL. You could select a shadowmesh too, but don't add polies (as boxes and spheres are the only 'dynamic' collisions (as far as i know )
you're finished with COL now. The only remaining thing is a entry in your object.dat
Open your object.dat, now search for 'interior door' you should see some entries, that starts with Gen_doorEXT10
Copy one of those, rename it to have the same name of your DFF.
| JVMETALDOOR, 5.0, 5.0 0.98, 0.1, 50.0, 0.0, 1.0, 0, 6, 1, 0, 0, 0.0, 0.0, 0.0, none|
And finished. your door should be working ingame. You don't need any special flag in the IDE/IPL for it.
Any questions you have, something that I didn't explain correctly... tell me.