If you already have DosBox installed, then just replace the EBoot.pbp with mine.
If you don't have it installed, then place the two files (Eboot and .conf) into "(MS0):\PSP\GAME\DosBox\" (if running an OE thats not using 1.50 kernel, then it'll be "GAME150"), the "DosBox" folder can technically be called anything you wish, but for simplicities sake, I chose DosBox.
If you need help with dos navigation and usage etc, may I recommend HERE for Ambirion's packs, they're for the old version of DosBox but they'll help get everything running. Just replace the EBoot in the pack with mine (hopefully Ambirion will post some updated packs at some point)
Cheers,
Fox