Never mind - fixed it myself, for anyone who is facing the same problem:
replace all occurences of
<format>{%CitationPrefix%}%RefOrder%{%CitationSuffix%}</format>
with
<format>{%CitationPrefix%}%RefOrder%{(p%CitationPages:p.:%)}{%CitationSuffix%}</format>
That's it - will result in [INDEX](pPAGENUMBERS) format.
Cheers!