You have some possibilities:
1. you can view the .tlk table with this application:
http://nwvault.ign.com/Files/other/data/1026158289672.shtml)
2. With kotor tool, you can view the dlg files by pressing crtl double click (but not very convenient if you want to read the dialog like a conversation. It's useful mostly when you are planning to edit a huge dlg file so you can have good look at the contents of the file but can't edit them with KT)
3. you can use TK102 DLGedit dowloadable at
http://www.pcgamemods.com/6/) . You can edit dlg files easily with this tool :)
4. If you have the NWN toolset, replace the ther original talk table by that of KOtor. Rename the orinial let's say to TLK2 and drop the Kotor tlk in the NWN folder. The buttons will be all wrong but don't worry, it works. Then open a module and drop the dlg file you want to see in the temp folder inside the module folder . You will be able to follow the dialog as a conversation. Note: do not use NWN toolset to edit dlg files. Many elements are not recogninze but NWN toolset, including the cameras. You'll have funny effects when you but it back in the game.