Help regarding the splitting of available screen size

Hi all,
   I am working on a project which requires the kernel to use only
half of screen. Other half of the screen will be used for some other
purpose. I will be running the kernel in text mode. I tried to do some
changes to file .drivers/console/vgacon.c to achieve this.
 I changed the value of vga_video_num_lines to half of its value, but
that didn't work for me.
 I am using the linux kernel version 2.6.24.7 for my project.

Could anyone please suggest me any pointers for implementing this .

Thanks,
Swapnil Pimpale