I was told by Asus Technical support you can disable integrated graphics and enable the Nvidia Discreet Graphics BIOS unless he was thinking in Windows 7. I need to look into this.
Well my particular laptop isn't the exact same as the posted one, however its the same family so they share similar hardware. Mine is the k53sv-xr1 has an q2630m i7 and nvidia gt540m graphics. The bioses should be very similar if not exactly the same. In my bios there are no options anywhere to disable the nvidia graphics card. Might be different though for different configurations.
Also you likely won't be able to use the nvidia graphics card, as far as i know, no one has had any luck getting hardware acceleration on the gt540m. I know one user tried to modify a next that allowed the gt520 series to work however it doesn't work on the 540s. The hd 3000 graphics works out of the box tho with Lion.