I have used Honda Moly 60 Paste on splined shafts for years with very good success. I have heard that Honda no longer imports this product but the Loctite 8012 product should work just as well. High molybdenum disulfide content pastes in general work well on sliding splined connections.
http://www.akd-tools.gr/xmsAssets/Fi...DS/8012-EN.pdf
Ted
I should have also said, just brush a thin coat on the splines. You don't want excess that will sling out onto the clutch disc.