Perhaps using panoutil?
PanoUtil 11-Aug-2013 Written by David Azarewicz
For use only when a compatible Panorama is installed
Usage:
PanoUtil [switches] function
Switches:
-v : verbose
Functions:
-i : display adapter information
-q : query current MTRR settings
-p [X Y] [d:] : Set PM resolution to XxY on drive d: (default 800x600)
-r [d:] : Reset custom resolution to default on drive d:
-d 0|1 [d:] : 0=Disable/1=Enable custom resolution logic on drive d:
-c X Y [d:] : Set Custom resolution to X Y on drive d:
-e 0|Clk,H,V,Hbl,Vbl,Hof,Hw,Vof,Vw [d:] : Set custom EDID on drive d:
-s [d:] : Show custom resolution status on drive d:
-n 0|1 [d:] : Enable/Disable Use Native Resolution on drive d:
-D n [d:] : Set Custom Desc Number on drive d:
-m <base> <size> <flag> : Modify specific MTRR
base is in hex
size is in decimal and must have a k or m suffix
flag is 0 for disable, 1 for enable
example: PanoUtil -m d0000000 64m 1
Looks like "panoutil -p 1920x1200 X:" (adjust X: to your boot drive) would work. Untested.