I have an asp.net checkboxlist as follows:
You should be able to apply the same methods to the CssClass property of your CheckBoxList control as you would a regular checkbox.
Here is some CSS code I used to indent long text next to an ASP.net check box list:
.chkChoice input
{
margin-left: -20px;
}
.chkChoice td
{
padding-left: 20px;
}
ASP.net: