Understanding Society User Support

I need to use an unemployment indicator that accords with the ILO definition (rather than just using the self-reported wJBSTAT). It seems that the variables needed to do so are not available for the early waves (for example wJUBGN starts wave F). However I have seen several papers that claim to use an unemployment indicator that fits the ILO definition for the first waves of BHPS. Is this possible? If so which variables do I need, as it looks like I would at least need wJUBGN (as well as JULK1 and wJULK4). I have also seen papers which claim it isn't possible which adds to the confusion.
Many thanks for any help.