Hi,
I have the 8.9 and was able to use the following with 100% success.
1. Open the Android Honeycomb browser on your tablet.
2. In the address bar, type: about:debug and press enter.
3. Now open the browser's settings by tapping the icon in the very top-right corner of your screen (it looks like four horizontal lines) and selecting "Settings" from the drop-down menu that appears.
4. On the left side of the screen, tap the section labeled "Debug."
5. On the right side of the screen, tap the item labeled "UAString," then select "Desktop."
6. Press the back button (in the very bottom-left corner of your screen) to exit the browser's settings.
7. In the browser's address bar, type: about:debug once more; this will disable debugging mode and return the browser to its normal state. [Optional] If you do this step you will need to redo this step every time to enable Desktop Browsing.
By the way, which version of the 8.9 do you have? I have the 7310, also known as the 16GB WIFI version.