But I saw my friend had some problems getting it set up and wanted to make it easier for other newbies so I figured I would do a step by step tutorial of how my friend got it working for his Nexus One.
Step 1: Download psx4droid in the android market (search psx and it will come up)
Step 2: Connect your phone to your computer via usb and create a folder where you will place your Bios file and Roms (SDcard -> then create a new folder PSXoid)
Step 3: google the term scph1001.bin and download the file
Step 4: place the scph1001.bin file in the newly created folder PSXoid
Now comes the tricky part with the roms since most of them have a wierd ECM file type that wont be recognized by your emulator; dont worry you just need to convert the file type to bin so the emulator can recognize it
Step 5: go to http://www.underground-gamer.com/wiki/index.php/ECM and download ECM under the Windows section of the page and extract the UNECM portion of the EMC download to the desktop
Step 6: grab the Rom in ECM format from the desktop and place it into the UNECM file now on the desktop, it will start making a copy of the Rom with the correct file type and will pull up a small black screen showing you that it is converting it to the correct format with a percentage ticking away to 100%
Step 7: now that you have the PSX Rom in the correct bin format, you can place it in the newly created PSXoid folder and your emulator will now be able to see it!
Step 8: unplug phone from USB and open psx4droid app
Step 9: Use the top portion of the settings to search for and select scph1001.bin as the bios file to use (It's easy to find since you know its in the PSXoid folder)
Step 10: Once you have selected the bios file you will be promted to find a rom that you want to use. You will now be able to see the rom and play it on your psx4droid emulator!
***Just a few tidbits in case people were wondering my friend is not rooted and this guide is for educational purposes only. Downloading illegal roms can get you in trouble and don't do it unless you have the original game you purchase.
EDIT: On Droid Forums a user by the name of Titan posted this comment when he was confused by step 6 ------ "Ah I got it working now, I get the .7z or .zip roms I downloaded, and I keep opening up the main folders/.zips until I get to a file called data.bin.ecm. Then I drag that to unecm. It seems that the "data.bin.ecm" is the game in all that mess. "