Use the ItemDataBound event of the Repeater, like this:
protected void rep_Comps_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
CheckBoxList chkList = e.Item.FindControl("chk_chkbx") as CheckBoxList ;
if (selectList != null)
{
chkList.DataSource = SomeDataSource();
chkList.DataBind();
chkList.DataTextField = "SomeColumn";
chkList.DataValueField = "SomeID";
}
}