[SB65]

Try:

#main-wrap #HCB_comment_box blockquote {color:white}

(The #main-wrap is required in the selector to give a higher specificity than this statement:

#main-wrap .container blockquote {
    background: url("theme/saperator-v.png?984031") repeat-y scroll left top transparent;
    border-left: medium none;
    color: #999999;
    font-style: italic;
    margin: 15px 0;
    padding-left: 30px;
}

- which is why the suggestion above doesn't work.)