This solution likely comes to late for you, but in case someone else has the same question:
Inspired from a solution somewhere else in this group, I simply added the following code in frontmatter.tex, under \tableofcontents
\clearpage
\phantomsection
\addcontentsline{toc}{frontmatter}{List of Abbreviations} % This adds the section to the TOC
\centerline{\expandafter\uppercase\expandafter{List of Abbreviations}}% This uses the same title format as other pages
\bigskip% Same spacing as other pages
\noindent WYWTA: what you want to add \\ % In general, \noindent removes default paragraph indent (also useful after equations)
\noindent AE: another entry