The numbers are the samples. So, for the loopstart the loop begins at sample <number> and the sample number for loopend determines when the loop finishes and then goes back to the loopstart sample location. To get the ogg to loop seamlessly you need the sample numbers to be perfectly on the beat. I've been putting in my own remasters of the soundtrack - I use Cubase Pro to produce my music and I can also use it to get hold of the exact sample number I need. So, if the loop begins at bar 4, I can go to bar 4 and copy the sample number for that exact location and then I go into a program called "audacity" (it's a free program), import my audio file, put in the metadata, then export it as ogg. There are probably other programs out there which can help you find exact bar locations and sample numbers, but since I use cubase I've never had to look around for any.
Hope that helps.