You can cross on a purl side, just reverse where the stitches go (hold in front or back) and purl the stitches.
So a right-leaning cable would have to have the stitches held in in the front on the purl side, purl the next stitches, and then purl the stitches from the cable needle.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry