June 24th 2015 Update: With the most recent version of Dark Souls, updated on June 24th, you will need this new version of DSMFix:
https://www.reddit.com/r/darksouls/comments/3ay9aj/dsmfix_update_for_new_steamworks_patch/

Note: This mod assumes you're using DSMFix (and if you're using mouse + keyboard, you really should be).
(edited: see update above)

It also assumes your mouse has at least 2 side buttons that can be bound to parry and block.

I was using another keyboard icon mod on here for a while, but it looked dated, so I went ahead and 'made' this. 99% of the keyboard icons are from here: http://opengameart.org/content/free-keyboard-and-controllers-prompts-pack

Big thanks to Xelu. The only icons I made were the arrow keys which I threw together using some of his provided images, and the mice. Many thanks to "iGooseman" as well, for the alternative, sleek weapon upgrade icons (if you'd prefer this mod without them, I've provided the files).

Installation instructions:
Make sure DSFix and DSMFix are installed properly. In dsfix.ini, change "enableTextureOverride 0" to "enableTextureOverride 1".
Put your chosen .png file into DATA/dsfix/tex_override.

As the file for button layouts (this mod) is separate from the game's actual keybindings, here is the list of keybinds associated with each key icon in this mod, to prevent confusion:

Esc: Open start menu
Q: Action, Enter (menus)
E: Use item, Unequip (equipment menu), Toggle Display (other menus)
(Alternative version: Q and E are swapped, for those who think E should be 'action' [me!])
Left Alt: 2-hand/1-hand weapon, Toggle Status (menus)
Space: Roll, Cancel/Back/Close (menus)
F: Cycle equipped items
R: Cycle equipped spells
C: Swap left weapon
V: Swap right weapon
G: Open gesture menu

Most of these are default, except Esc, Q, E, Alt, and Space for menu use. I highly recommend changing this, which can be done from Options>Key Settings>Menu Control [last tab]. Make the following changes:

Confirm = Q (E if using alternate)
Cancel = Space
Menu function 1 = Left Alt
Menu function 2 = E (Q if using alternate)

And to bind 'Open start menu' to Escape:

Options>Key Settings>Menu Display [2nd last tab]>Open Start Menu = Esc

If you want to use the alternative version of this mod, make sure you swap Q and E in the "Actions" keybind menu (4th tab), too.

That's it. These menu controls are much more intuitive than the defaults, and also match up with the controller bindings (Cancel and Roll on the same button, Action and Enter on the same button, etc.), which might make you wonder why these weren't the defaults in the first place.

I will provide the PSD file, as much of a mess as it is, in case somebody wants to edit it.

Now go and show the world you can use a keyboard and mouse just fine with Dark Souls.