@White_Wolf: Have a look at the manual, there's a detailed explanation under
PATH"dirname";
and
#define PRAGMA_PATH"path";

You can check the string exe_dir, it should contain the location of your acknex.exe. For relative paths (I think) you usually do not need %EXE_DIR%. I use a wdl file (see manual) that contains my paths as follows:
superku.c - main script
superku.wdl - contains relative paths suchs as PATH "Sounds";