Converting any stitch pattern to make a triangular shawl

I would like to use a lace stitch pattern from Barbara Walker’s #2 book to make a triangular shawl rather than a rectangular shawl. Is there any way this can be done?

If you start from the neck dow, begin in the usual way - CO enough sts for edge, yo, k1 yo K1 (center st) yo, k1, yo, edge sts. Then for the WS knit the edge sts and purl the middle sts. Repeat that first row - edge sts, YO knit to center st, yo, knit to the end YO, edge sts - and the WS rows until you have enough sts to make a stitch repeat on either side of the center st, still adding the YOs on both sides of it and each end. Depending on the pattern, you may want to put a marker before and after the lace repeats, keeping the new sts in stockinette until you have enough to do another lace repeat. Then move the markers to before and after the new lace repeats.

It would be a good idea to make a sample (can also be used as a swatch for needle size) in the original pattern as written, about 2 pattern repeats wide by 3 repeats long, and keep that as a guide to make sure you’re staying on pattern as you increase the sts.