Not having tested anything, but...
Even if external links would be supported by the iPDF viewer (I have no idea)
you have to account for the fact that your average iLiad file gets moved
into a folder having the same name as the original by the iLiad.
This breaks even the most relative path you may come up with, because
not just your target but also your "table-of-contents-pdf" gets moved
one level up (or down - never got the wording right) in your directory tree...
Just my two EUR cent...
Dirk