since you want to control all aspects, including hover, you would be better setting each menu Item LI tag to have a unique ID:
<li id="donate"><span><a href="<url goes here>" target="_blank">Donate Now</a></span></li>
then create rules to target the indvidual ID such as:
ul#cssmw3 > li#donate
ul#cssmw3 > li#donate > span
ul#cssmw3 > li#donate > span > a, ul#cssmw3 > li#donate > span > a:link
ul#cssmw3 > li#donate:hover
etc...
basically copying each existing style, and targeting to the specific ID using "#idNmae" after the LI
this way you can still control the pseudo classes like :link and :hover