I made modifications to knit a beanie.

The decreases are the same for both beanie and Tam.

Shape Crown:

Decrease Row 4:

Move 1st stitch behind stitch marker

Slip 1st stitch

Color 1 - knit 2 times
Color 2 - knit 3 times
Repeat 3 times

Color 1 - knit 2 times

Remove stitch marker (using one stitch before and one stitch after stitch marker)
S2KP (second color)

Replace SM

18 stitch count between stitch markers.

The S2KP will be the first stitch for each SM

Same for all decrease rows