Generating tags for sources in non-writable directories

Hello,

Here are the situation I have. I want to have tags for a project and all its
dependencies. The problem is that the dependencies are in folders where I
don't have write access.

I can generate tags in other directory, but GPATH contains then relative
paths. So when trying to use global on it, it find the correct tag but doesn't
output the correct path.

Is there any solution for this problem? I didn't find any. There is the --path
option, but if I understood well, it is only a filter for output. Then I could
not use it as there are more than one dependency and I want to search through
all of them. So I can't know what will be the correct absolute path before
running it.

Any help is welcome. Do not hesitate also to tell me if you need more
information about what I'd like to do.

Thank you very much,

Christian Jodar.