Alternating comment colours in a buddypress theme

Hi there,
I am using(customising) the jukt microelectronics theme and would love to have alternating comment colour (backgrounds) and possibly user highlighting.
I think I read somewhere that alternating comment colours was a feature of wp 3.0x but all the stuff i can find was for older version of wp (2.7) and those are supposed to no longer work.

Is there some simple way of implementing this. I though i would add the buddypress bit as this complicates things slightly by using a plugin theme and then a sub theme on yop.
Anyway thanks if you have any ideas
David
edit – i have read this but not sure how it is implemented
https://codex.www.ads-software.com/Migrating_Plugins_and_Themes_to_2.7/Enhanced_Comment_Display#CSS_Styling