Is there any way to make the nslLocalFile Component working with relative paths?
Relative to what? To the binary that is launched? You can get the binary location from the nsIDirectoryService (see NS_OS_CURRENT_PROCESS_DIR from nsDirectoryServiceDefs.h).
Then you can use nsIFile/nsILocalFile to "append", "appendNative", "appendRelativePath", or "appendRelativeNativePath".
--BDS
