Easiest way is to put this in your build script:
find path/to/package -name '*.d' | \
xargs grep '^module ' | \
sed 's,^module,import,' \
> data/modules.d
Add `-J data` to your DMD command line, or add `"stringImportPaths":
["data"]` to dub.json.
Then in your file:
mixin(import("modules.d"));