How to make a pattern wider?

I decided to take a break from challenging projects and do something easy and fun and relaxing, and I chose a pattern that helps to work on my lace technique. However, I think that it is going to be a very narrow scarf and would like to make it wider. I was just going to knit to whatever length I could get to, but making it wide is much harder when there are increases and decreases.

There should be a way to figure out that it needs to be increased i.e. 4 extra cast on stitches, however many times as needed.

Link to the Scarf Pattern

Yes, you can add in multiples of 4 sts.
Did you see the correction here?
http://www.ravelry.com/discuss/patterns/2304710/1-25#reply_form