You can't do that. Every clock cycle of the pixel clock that is in the valid display region will write the parallel data to the given pixel. If you set the output for one pixel clock, and don't then change it for the next clock, you will just end up with a long line. You can't just skip a pixel willy nilly.
Take the nokia 5110 LCD or my personal favourite the nokia6100 LCD. You have a serial bus which allows you to address a pixel. You say, i want to change pixel (a,b) then say what you wan't it to be. They have an high level controller and frame memory built in.
This display is for lack of better word dumb. You can't just address a specific pixel - there are no address lines! Its an all or nothing.
The only way you can do it is to slow the pixel clock down to a rate at which the arduino can be the frame buffer and offload every pixels worth of data. I have been messing around with this, and after some very heavy optimision, using a parallel SRAM, writing large parts in assembler, and heck even choosing certain IO pins as they are faster to write to... The absolute maximum i can get it to do is 333KHz for a similar sort of display. Now if i went down to 8 bits per pixel (256 colours), I can get that up to 500kHz. However that is a far cry from the absolute minimum of 5MHz that the specific display requires.
It CANNOT be done with an arduino alone. (period)