As fatcat said interval training does seem to be the in thing at the moment it even made yahoo news:
news.yahoo.com/s/ap/20100225/ap_on_he_me...med_intense_exercise
I've not tried it, but I think I'm going to be.
I can't really comment on high kicks, as silat as a rule doesn't kick above the waist, but I know even those can get exhausting if you do enough of them.
I say in this case just train with the kicks; it's going to be CV training anyway, and it will be training all the muscles you need rather than potentially just some of the muscles from if you were running.
I've noticed that my fitness for silat has increased incredibly, but my fitness for other sports has only increased a little. It stands to reason that the opposite would also be true.