You have to clock in every pixel and to generate HSYNC and VSYNC.
The exact howto depends on the type (STN, TFT, s/w or color) of your
LCD. Theoretically it can be done with an 8051, but the problem is
the performance. You have to update your 25'600 Pixels every 20-30ms.
This gives a throughput of over 1'000'000 Pixel/s. I think this would be
critical with your 8051.
Another possibility is to share RAM with a CPLD that does this stuff.