Thanks a mil, Karnij! What program did you use to do this, and how? Quite an useful trick to know.
You're welcome! I love extending tracks, so I was more than happy to come across this and help out.
I use a program called MP3 Editor for Free (
http://www.mp3-editor.net/). I got it since I usually find MP3s of tracks I want to edit over most other formats (not really a lossless FLAC kind of guy) and, while you cannot save your work as an MP3 unless you purchase the program, you can save as a WAV file without any problems.
I listen to the track a few times to get a feel for where the loop start and end point is (or where I am going to make my own if I can/have to) and then I zoom in quite a bit. Sometimes it truly comes down to getting the milliseconds just right for the loop so string together seamlessly (aka no pop or crackling sounds). For example, with the Ruid track, I tried a few different points before using the start point of 6.351 seconds and ending at 56.888 seconds turned out perfect. A little before or after that at either point produced a pop/crackle sounds that I hate to include in my extensions (though sometimes it is unavoidable) or there would have been a noticeable pitch change (this, too, is sometimes unavoidable if you are really itching to extend a track that clearly has no loop point you can work with. I mangled a few of the arranged tracks from Virtua Fighter 2 by trying to extend them, but ya never know until you try).
Honestly, the stuff I wrote above is probably confusing and my best suggestion would be to download the program I linked above and just mess around with a few tracks so you can get a feel for what it is like (after all, you don't have to save them or anything). That is how I learned how to do this, and I feel like I'm still learning little tricks with every new track I try. The program crashes a lot if you are playing the track on it (but you have to to hear if the loop sounds right), so I would also suggest writing down your loop points if you feel you are in the right area but need to tweak them a bit just so you can go right back to them once the program is back up.
I hope this helps and that I have not dissuaded you from trying with my rambling explanations.
(Yep, shameless self-promotion in my sig)