Open SKS. (skinstudio). Load the skin you want to change. On the top left of SKS click on "Open skin" Scroll down the list and find the skin and double click on it. Click on Edit Statmenu and Taskbar. Now click on "EditStart Menu". When th ewindow look for "Left hand side". Go to "item Mouseover" and click on it. Go to "text" at the bottom and click on it. Where it says "Text Color click on the arrow to open a menu. Pick you color and click "Apply skin"
Some skins have an item mouseover in the "Right hand side" also if you make that the same color.
If you want to change the arrows color on the startmenu do it with the same window open. Just click on the "Left hand side" "Programs list" Text setting and change the color. Do the same on the "Right hand side" "Places List"