Not sure if the Pandora's WiFi is capable of it. I would probably set up an SD card to boot from (either Pandian or Slackware). You'll need to install hostapd and probably isc-dhcp-server (that's why I would boot from SD).
This may already be all you need though ... you then have to create a proper hostapd.conf and edit /etc/network/interfaces and /etc/dhcp/dhcpd.conf. This is how I set up a BeagleBone running Debian, you'll probably find tons of information (and probably also slighty different ways to set it up) if you google for guides setting up a Raspberry Pi or BeagleBone. Also check the Debian and Ubuntu Wiki, they both have useful information on how to do it.
EDIT: thinking about it a bit more - since you probably just need something to connect your DS to and then do nothing - you probably don't have to edit /etc/networ/interfaces, just get hostapd and isc-dhcp-server, create a basic hostapd.conf, edit /etc/dhcp/dhcpd.conf and then manually start hostapd.