I'd rather see that as a separate indicator. Largely because 'nationalism' took many forms. That is, rather being a distinct ideology in its own right, every one of the existing political categories has some nationalist variant. So you'd get 'conservative nationalists', 'liberal nationalists', 'fascist nationalists', etc. In Weimar Republic these would be the DNVP, DVP, and NSDAP respectivelyNationalism/Separatism
It might be better to either leave nationalism as a political issue or modify 'consciousness' to account for it. Perhaps using two categories - 'national consciousness' and 'class consciousness' or making them opposing poles on the same meter. That way socialist POPs that have high national consciousness will either vote for a social nationalist party (such as the Polish Socialist Party or Irish Labour Party) or switch their loyalty to a liberal-nationalist party, for example
Come to think of it, isn't that how its already handled? A POP with low consciousness is more likely to vote for parties on the basis of single issues... such as citizenship policies