Took me hours and multiple calls to Dell Technical Support to find this information out. The Dell Zino HD uses the following IR standard for the Remote Sensor on the front:
Here is the PDF specification: http://www.datasheetcatalog.org/datasheet/nec/UPD6600A.pdf
The support representative said most universal remotes use one of these two standards:
Unfortunately, this causes issues when trying to use a universal remote (example: XBOX 360 Universal Remote) with the Dell Zino HD. A USB External IR sensor is needed to work with most universal remotes. This is very confusing, as both devices list as a standard "Microsoft eHome Infrared Tranciever".
What this means is that no remote -- other than the one that shipped with your device -- will work with your Dell Zino HD! Scroll down to see my work-around.
Since the Dell Zino HD only comes with 4 usb ports, the external sensor may have to be plugged in to the front of the device, which is particularly clumsy looking. (The back two ports on my device are used by HDTV tuner and Wireless Mouse/Keyboard dongle.
If anyone finds an affordable remote that is compatible with the Dell Zino HD front sensor (other than the small Dell remote that ships with the device), please post a reply here!
Update: The on-board IR sensor uses a USB header similar to that inside an optical mouse (pinout is different, wire colors are the same). Getting to it is easy - Do this at your own risk! (1. Release the lid from the back of the Zino, 2. Remove 2 screws. 3. Slide back and lift metal cover from front and drape over back. 4. Disconnect power/sata wire from back of CDROM, slide cdrom out front. 5. Unhook antenna wire from hard drive carrier. 5. Remove 2 screws from hard drive carrier. 6. Slide hard drive carrier back and pull out gently. 7. Disconnect power/sata wire from hard drive. 7. Disconnect power button/led plug. 8. Gently lift clip holding in IR sensor. 9. Disconnect IR sensor USB header from motherboard.)
I took apart my external USB sensor, cut off the repeater wires (the wire leads going to the headphone-style plugs) and switched the wire order.
Here's what the stock dell sensor looks like. Don't pay attention to the plug as it is soldered on. (click to enlarge):
Back ("Wire") Side / Front ("Sensor") Side
Here's a picture of the USB header going to the motherboard. This wire is about 2" long and goes directly from the IR sensor to the motherboard. Using the mouse wire, we can reproduce this plug without destroying the original sensor (click to enlarge):
Here's a picture of the inside of an optical mouse. I used the wires and plug connecting to the inside of the mouse as a plug for the Zino HD's motherboard. Notice the pin order (this may change between manufacturers). (click picture to enlarge).
Example of a standard USB mouse. The white plug is what was used.
*Note: Taking apart the Universal Remote sensor (my external one) wasn't easy as there were no screws holding it together. (Your external IR receiver/tranciever may differ). I compressed the plasic casing in a vice slowly until I could break it apart. Once it was apart, the rest was very self explanatory.
Left-over parts from external USB IR Sensor
Unfortunately I don't have any pictures of the finalized sensor and cable. I wrapped the small circuit board in black tape as it didn't fit perfectly and didn't want it to short-out on anything. I laid it flat and it just barely fit underneath the hard drive. Make sure the sensor is closest to the IR window. Hopefully someone else will do this same modification to their Dell Zino HD and submit some pictures in the comments!
I now have a working Universal Remote Sensor mounted internally in my Dell Zino HD!