This post shows a video of how to do a speed swatch.

For the Galloway Cardigan, knit two separate speed swatches for the Lice Stitch section and the Colorwork section of the sweater. Block and measure the swatches. If either or both of them do not meet gauge, rework the swatch(es) until you end up with swatches that meet gauge. Make not of the needle sizes.

For both swatches, cast on 29 stitches (6 st repeat x 3, + 7, plus 4 selvage stitches, two on each end.)

For the Lice Swatch, follow the chart on page 15 of the pattern rows 19 through 28. Knit those rows a total of 4 times. For every row you're using both colors on, knit the first two stitches with both colors, work the pattern, and then work the last two stitches using both colors. Carry both colors across the back and then knit the first two stitches on the next row with both colors. Knit the solid color rows using only one color --- do not carry the other color along the back of the solid color rows.

For the Colorwork Swatch, follow the chart on page 15 of the pattern rows 36 through 63 one time. Here's how to deal with the selvage stitches when you changes colors between rows.

For row 1, using colors A and B, knit the first two stitches using both colors, then work the chart, and then work the last two stitches using both colors. Carry both colors across the back and then knit the first stitch using colors A and B. Knit the second stitch using colors A and C, dropping color B. Work the chart and knit the last two stitches in A and C. Carry A and C across the back, knit the first stitch of the next row in A and C. Proceed in this same fashion.

Be sure to respect color dominance. The dominant color in the chart on page 15 should be held in your left hand if you're knitting using a color in each hand.

Also, watch the video on how to capture your floats. There are also a couple of blog posts with step by step instructions and photos of how to measure gauge.