autopkgtest with additional data files?

For one of my projects (density-fitness) I'd like to have a better 
autopkgtest that does not require a full installation of libcifpp along 
with the 750MB of data in components.cif (CCD). So I rewrote the script 
to run the executable in order to use a small subset of that CCD file. 
But the autopkgtest cannot find the file which means the script is not 
run from within the directory where the test files are located.

What is the best approach to fix this? Use the path of the script 
querying $0? Use some undocumented variable to find the location of the 
scripts? Include the data into the script and write that out first 
before running the actual test?

-maarten