From the algorithm dialog you should see something like this:

which is a call from GDAL using Processing. So, I think it should be enough starting from it for creating your own script.

You may try using this code (you should edit the com_string string by adding your specific parameters, including the extra flags):

import os, gdal

com_string = "gdal_rasterize -a KRK_1 -ot Byte -of GTiff -te Extent -tr cellsize cellsize -co COMPRESS=NONE -co BIGTIFF=IF_NEEDED -l Input"
os.system(com_string)

As a first step, I suggest you to initially copy-and-paste only what you see in the Processing dialog after having set your input parameters, and then trying to add your extra flags in the code.

From the algorithm dialog you should see something like this:

which is a call from GDAL using Processing. So, I think it should be enough starting from it for creating your own script.

You may try using this code (you should edit the com_string string by adding your specific parameters, including the extra flags):

##Rasterize_GDAL_KRK=name
##Input=vector
##Output=output raster
##Extent=extent
##cellsize=number 25

import os, gdal
import processing


ex = Extent.split(',')
ext = str(ex[0]) + "," + str(ex[1]) + "," + str(ex[2]) + "," + str(ex[3])

com_string = "gdal_rasterize -a KRK_1 -ot 0 -of GTiff -te " +  ext + " -tr " + str(cellsize) +" " + str(cellsize) + " -co COMPRESS=NONE -co BIGTIFF=IF_NEEDED -l " + str(Input)
os.system(com_string)

As a first step, I suggest you to initially copy-and-paste only what you see in the Processing dialog after having set your input parameters, and then trying to add your extra flags in the code.