As per my knowledge Q2A doesn't store any user specific information in question or answer for votes. So I think you may need to create a plugin using custom tables.
You can use vote event to insert the data. It will allows you to get all information related to question, answer and user. See here
'q_vote_up', 'q_vote_down', 'q_vote_nil', 'a_vote_up', 'a_vote_down', 'a_vote_nil'
So on event just get data and insert into table and than run query to list them all. This would be interesting plugin..... If you want my help let me know I would like to work on this.