how to harvest translatable strings from generated files?

[Paul Pogonyshev]

Hi,

I have a custom-format files which a parsed during build process with custom
tools to generate C files.  Some of these files contain translable strings.
Apparently, I cannot feed the custom files to `xgettext', because it doesn't
understand their format.  At the same time, C files end up in the build
directory, which is not necessarily the same as the source directory.

Is there a way to feed the strings to `xgettext', either from the custom
files (how to make `xgettext' understand them?) or from generated C files
(how to make `POTFILES' contain pathes to the build directory?)  I'm using
Autoconf/Automake.

Thanks in advance.

Paul