I recently did something similiar only with an HP laptop, hopefully this can help you a bit cause I had nothing but trouble trying to set it up! I think this was mostly due to the UEFI settings in the BIOS which are quite hopeless.
My laptop came with a 1TB hard drive in it but part of the reason I bought it was because I knew it was possible to add an msata drive as boot and keep the 1TB as storage. I found a guide for a different model of laptop, still HP, and it helped but didn't cover everything. This is to do a clean install on the msata and wipe the old system I had on the HD.
Here's the guide 1">[click here program used to make a bootable USB was called Rufus. I imagine the situation with the intel drivers is probably the same, you should be able to get them off the DELL website.
Link to the version of Windows 8 I used is here 2">[click here
I know you've got 8.1 so you might need another iso. The Windows key on my laptop is built into the BIOS, I used a program to find out what my key was then tried to use that to download Windows the official way but as it was OEM I kept getting error messages. The iso I linked is for an RTM version of Windows 8, it automatically got the key from the BIOS and I was set up with my offical licensed verion of Windows 8, I then ran all of the Windows updates and upgraded to 8.1 for free in the Windows store. My only problem now, and it's not a major one really, is that if I go into the BIOS it pretty much stops Windows from booting. Only way to fix it is to remove my HD and fix the boot from msata. Shouldn't affect you though. Anyway, hope this helps, I was pulling my hair out after a few hours trying to get this to work! My laptop now boots in about 17 seconds I think which isn't far off my desktop! The