How to play
This mini-guide assumes that you are familar with the process of running homebrew on your Nintendo DS. If you don't know how to run NDS homebrew, look online for the answer...

You need Quake's data files. If you own a copy, that's cool - you'll have full access to the game. If not, then you can download the shareware version of Quake (for DOS) from id's site. This will only allow you to play the levels from the first episode. If you want to play the full game, buy a copy - don't ask me (or others) where you can get these files.

In the root of your flash card, make a directory named id1
If you're using the shareware version, copy pak0.pak from that archive into the id1 directory that you just created
If you're using a commerical version, copy pak0.pak AND pak1.pak into that directory
You need a config file to tell the game how buttons are set up, etc. I know that my config file works, so download that from the link above and save it into the id1 directory.
Visit Chishm's DLDI page (above) and download the DLDI driver file which corresponds to your NDS booting method.
Download the QuakeDS binary package above, and extract the NDS file into the root of your flash card
You now need to patch that program so that it will be able to access the files on your card
For example, on my GBA Movie Player (CF) I download the file named 'mpcf.dldi' from Chishm's page.
I then run 'dlditool mpcf.dldi k:\QuakeDS.nds' - note K: is the volume where my Compact Flash card is mounted, yours will likely differ

Now do what you've gotta do to make an NDS start on your card
For example, on my GBA Movie Player, I need to rename K:\QuakeDS.nds to K:\_boot_mp.nds
Put the card in your booting hardware and turn on your DS!

Controls

The game is not currently finished, so there's no control customisation, bar what you can hack up in in_null.c and config.cfg. You will be able to properly change the controls in the finished version.
Current controls:

touching the screen changes the camera view
using the D-pad emulates the WSAD control method, so use up and down to move forward and backward, left and right to strafe left and right
B is bound to escape, so this will bring up/hide the menu
A is bound to enter, so can be used to select entries in the menu...and also jump
X/Y are weapon cycle up/down
L is fire
R is bound to god mode