There are tools to help dump and insert test (cartographer and atlas being the big two, you may also like Kruptar 7) but they do not always work the best with modern console text formats (they are built more for set memory locations and the like).
Usually then you find a programming language and teach it how to read your text table (up to you if you want to render it in the game's font), handle your pointers should there be any, handle any markup if it is not part of the font, handle any variables if such things are present and so forth.
You may or may not want to do line/section length checking, if you are exporting to text you have to both figure out a way to export it so others can read it (I usually use square brackets with readable text* or XML style markup) and a way to import it back again (including fixing the presumably altered pointers). If you are doing a 16 bit to 8 bit conversion then you also have to account for that, most of the time this is just a matter of having an export table and an import table.
*an example might be
You need to get the [italic]rusty spork of destiny[/italic] to enter this palace.
Basically any general purpose language will do here. If you already know one then go with that, if you do not know any then you have several choices. For the most part though it boils down to C#, python or java though not many hackers use java (thankfully).