The 37-year-old, a Scottish Cup winner with Hearts in 2006, will work alongside new manager John McGlynn and first-team coach Gary Locke.
The Lithuanian, who won two European trophies under Jose Mourinho at Porto, spent last season in the same role at Lokomotiv Moscow, where he worked alongside former Kaunas manager Jose Couceiro.
7.45 unless stated
Uefa Champions League. First qualifying round, first leg: Linfield v B36 Torshavn.
Uefa Europa League. First qualifying round, first leg: Shkendija Tetovo v Portadown (4.30).