Nice, I got this working too. Thanks for letting us in on the p910nd software! I'll attach my compiled copy. You don't have to recompile the kernel any more to enable USB printer support, since newer unRAID versions seem to already have this enabled.
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Edit added 9/4/2015--Support for unRAID 6.x
I've recompiled and attached a p910nd version that works for unRAID 6.x. unzip the file and chmod +x p910nd. The commandline stays the same, p910nd -f /dev/usb/lp0 -b.
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To get it working, do the following.
1. Put the attached p910nd file somewhere in your flash drive's /boot folder.
2. Add two lines to /boot/config/go so it runs automatically when you boot: 1: mkdir /var/lock/subsys 2: /boot/</yourpath>/p910nd -f /dev/usblp0 -b
3. Attach your printer and reboot or manually run p910nd. Check /var/log/syslog and make sure the kernel saw your printer and that p910nd isn't showing any errors. I had to manually create the /var/lock/subsys/ folder before it would load error-free.
4. Go to www.samsung.com and download the driver for the printer. If you're using Windows, you must download the actual GDI driver, not the universal driver.
5. Install the printer driver. In Windows you'll end up with an ML-1710 printer in your Printers folder that's connected to LPT1, which won't work.
6. Click Properties on the ML-1710 printer and go to the Ports tab. Click the Add Port button.
7. Select Standard TCP/IP port and click the New Port button.
8. In the Add Port wizard, put in your unraid name or IP address. Give the port a name. Click next. The wizard will freeze for a bit.
9. On the Additional Port Information Required page, click Custom and then the Settings button. Make sure the info is correct. The port should be 9100 and the protocol should be raw. Click OK.
10. Click Next and Finish to finish the wizard. Close the Printer Ports dialog.
11. Your new port should be selected in the Printer's port list. Click the Apply button, go to the General tab and print a test page!
I imagine this process would work for any printer that has a driver with raw printing and custom port support. Good luck.
p910nd.zip
p910nd-unRAID61.zip