Oxygen XML Editor Author allows you to set the value of the list-style-type property to -oxy-lower-cyrillic-ru, -oxy-lower-cyrillic-uk, -oxy-upper-cyrillic-ru or -oxy-upper-cyrillic-uk, meaning that you can have Russian and Ukrainian counters.
li{
display:list-item;
list-style-type:-oxy-lower-cyrillic-ru;
}