Board of directors- selection process

Hi,

As part of an independent research work, I was asked to find out how can someone forcefully make their way into board of directors of company which is publicly traded in Germany.
Upon initial research, I found out that German companies have two tier board structure.
1) Management board - which will be selected internally.
2) Supervisory board.- which would be selected by shareholders and the employees of the company.The latter is is because of the co-determination rule. (I would be really glad if someone could provide further details on this.:D)

I am assuming that if someone who isnt related to the company wants to be in the board, the only way to to buy significant number stocks of stocks in the open market and try to get selected into supervisory board.

If yes, what percentage of the stocks should he buy.

Really appreciate if someone could shed some light on this.