Yes! Very doable!
I have two 2TB drives in my home system as a media server. I put both in.
Here's the IFIXIT guide: Installing Mac Mini Mid 2011 Dual Hard Drive Kit, Here's the kit: Mac Mini Dual Drive Kit which will give you all of the pieces.
As for the drive, all you need to make sure of is the hight of the drive does not exceeds 9.5 mm and is a SATA III (6.0 Gb/s) drive. If you can swing it I would recommend getting a Seagate SSHD drive Vs a standard drive. Hybrid drives offer deeper caching which speeds up the boot up and launching of apps. Heres a link to the Seagate page that talks about it: Laptop SSHD.