I recently perchased a G53S with a seperate Intel 510 120GB SSD. This is how I installed it and got it working with Win 7 Home Permium and all the ASUS Utilities. Hopefully you can do it too.

Requried Items:
SSD
4gb USB drive or empty DVD

I started off watching this video from xoticpc.com and it explains how to access and install the disk.

I installed the SSD to the primary harddrive slot and moved the HDD to the secondary slot. To do this you will need to flip the bay rack of your HDD in order to get it in the right way.

Once you have the disk installed you might see it along with your other disks under My Computer. But mine dissapperd after a few reboots and I couldnt access it anymore. So I opned cmd /w admin rights and wrote:

(This will format your SSD. Unless you have a blank/new SSD or dont mind wiping it clean, don't proceed)

DISKPART
LIST DISK (Find the number your new SSD, if you installed it in the primary slot it will be listed as DISK 0)
SELECT DISK (Number of your SSD)
CLEAN
CREATE PARTITION PRIMARY
SELECT PARTITION 1
ACTIVE
FORMAT FS=NTFS
ASSIGN (Your SSD should now be mounted and reccognized by windows)
EXIT

If all that went smooth you now have your SSD up and running NFTS filesystem.

Next I downloaded Windows 7 Home Premium from a torrent site and put it on a USB drive. You can also burn it to a DVD.
Restart your computed, press F2 to get into BIOS and change the boot priority to either USB or DVD (depending on what you use) and install Windows on your SSD. If you need help on making a bootable USB you can follow this guide. With a downloaded Windows ISO-file you will need to mount it with your prefered virtual disk utility (MagicDisk, DeamonTools, etc) and copy the files from the virtual drive. Copying the ISO-file to the USB will not work.

When setup is complete pop in the ASUS driver DVD that came in your box and install everything.

After a dusin reboots you are done 😃

Hope this guide will serve useful. Please post questions below and I will do my best to help you out.

Regards