Enlarging the content outside of the software would cause it to become heavily pixelated and I don't know if it would be possible to work around that.
If the above is true...then I guess you could either just magnify the window using the Ease of Access stuff build into windows, or I guess something could be hacked together that would simply to the exact same thing (IE: Look at a window in the background and overlay a magnified fullscreen version of that window)...Again...Not pretty, and if the window is as small as the GBA Emulator I have...I highly doubt you would be able to recognize anything beyond 800x600 resolution, let-alone 1920x1080 :/