I am not sure if anyone is interested but on reading the /etc/slim.conf file i noticed that there was an option to use either /etc/X11/Xsession or ~/.xinit. So i added the xrandr configuration to Xsession after the variables files and it seems to have worked
# initialize variables for use by all session scripts
#Try to use xrandr
xrandr --output LVDS1 --off --output VGA1 --mode 1280x1024 --rate 75
I am sure that the more correct solution would have been to utilise one of the mentioned configuration files.. but at the moment i am just glad it works.
If anyone is kind enough to criticise this please do so.