You can do any of the single-strand cast-ons with your working yarn. The knitted or backward loop would work well for this.
Check out Amy's videos in the casting on section.
Just get to the end of your row and continue with the cast-on stitches.
"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