You could have given little more information about your recruitment campaign. What is the nature of your industry? What is the education level of job candidates? Where the recruitment will happen and what would be designation allotted after joining? How many vacancies you need to fill? How many persons will be involved in the interviews?
Since this is a mass recruitment, let me assume that it must be for freshly passed graduates or post-graduates. Nevertheless, if 600 candidates are expected to turn for the interview then your company must have handled similar campaign in the past. Why not to utilise that experience? Secondly, if VP level officials are likely to participate in the selection then are they are not to guiding you on designing the flow of the entire recruitment process? Why a need was felt to ask the suggestion in the public forum?
As a solution, I can recommend you conducting aptitude test or logical reasoning test. Generally these are conducted through Multiple Choice Questions (MCQ). This is the best filter at the first level. You can have 30-40 questions and you can allot 30 minutes to reply. Even by using manual method, there is smart way of working and it just takes 30-40 second to assess one answer sheet. Therefore, no computer or software is required. In the first round weed out 80% candidates and retain just top 20% Possibly it may take about a day to handle the entire process. To handle this round, you need to have a hall in the education institution.
At second level, conduct one more test that is related to the nature of job that they will do. In this round eliminate 5-10 more per cent depending on your vacancy requirement.
On the third day, or in the second half of the second day, you should conduct interviews for 50-75 candidates depending on the requirement.
If your company has sufficient funds, then you may hire services of the education institutes that impart coaching classes. The first round of selection can be outsourced to them. They should be able to give the results in soft copy. However, you have to prepare the question paper and answers for the questions and give it to them.
8th March 2016 From India, Bangalore