Well there's a few ways to go about something like that...
Personally, I would think the simplest way would be to use that modified spells.2da so armor doesn't restrict force powers, and then hack the feat.2da and simply give light, medium, and heavy armor to jedi as freebies at level 1 for all 3 jedi classes.
Just edit the 3 lines for the 3 various armor feats, changing the values of the following labels to have a value of 1:
allclassescanuse, jcn_list, jcn_granted, jgd_list, jgd granted, jsn_list, jsn_granted
Then all jedi would get all the armor feats for freebies at level 1 and you'd already have fixed the problem of it bothering force powers.
This would be IMO the simplest way.
The other way would be to manually edit evrey single piece of armor you want to be able to use.
You'd load up Kotor_tool, then open up the BIF files. Once it builds the list, you'd open the "templates" entry.
Most armor is "g_a_classNNNN.uti" but there's a couple special ones here and there if I remember right that use g1_a_classNNNN as well as one or two that have completely different names. If you have a list of cheat codes and possible items you can spawn into the game, those numbers match up here.
Anyways, you'd have to figure out which entry is which item in game, then export the file to the \Override folder. Then using the GFF Editor, you'd edit these files and manually change the properties individually. You'd have to change the "BaseItem" from whatever value it was (should be 38 - 43 for non-robe armors) to 35 (Jedi Robe), 36 (Knight Robe), or 37 (Master Robe).
Then save the file. I THINK that would work anyway. lol.. like I said, I'd probably just add the feats
Oh, you could also create a totally new item by saving the file you exported with a new (unique) name. Then you'd have to add it in game with the console codes, using "giveitem <your_item's_file_name>" without the .uti extention so as not to alter an existing piece of actual equipment in the game at your discretion. =)