As TKaos said no one around has access to the iso site/db i think (apart from idoru).
Also, don't want to demotivate you or something but i wouldn't expect access to it at all. Just think about it, no project that i know (not only rom related) will provide all their data and code to someone that asks for it, only if they are opensource / free / available from the start. Things don't work that way. Usually, at least around here, people came along and start to participate and being part of the community, helping out with smaller tasks and after a while they get more and more involved, once they understood all the details and showed they are really interested in the project.
I may be wrong, obviously, but you will have to wait for someone from ISO part to reply to you, maybe they need some updates and improvements on their system or need to add something new and your help will be really appreciated then.

Also, i already said that i have really no idea on how toseciso works. I guess for the Jaguar case (doesn't appear listed) is that those dats are probably made somewhere else (i see no point in having the system there as hidden). You may also try to ask for details at dumpcast, the group(?) that dumps tosec dreamcast sets
