How do I make consoles or computers? I don't mean skinning them but open a "conversation" with them.

Attach a dialogue to them, essentially. Same as with a creature. tk102's dialogue editor has the option to set the dialogue type to "Computer" - click on the root node (where your dialogue's file name is) and you should be able to alter things like that. It's been a while so I forget whether or not you have to attach a script to standard placeables to get them to talk. If you do then: in TSL you can attach a_compdlg to the OnUsed script and in KotOR attach the following script to the same field:

void main()
{

ActionStartConversation(GetPartyMemberByIndex(0));

}