I have a WS2812, which I believe is the same as a 2811, just a US 'big box' discount store version, the faceplate on the display panel might be different.
First, set the WS2812 in its 'rapid' mode via Heavy Weather (Tools -> Options, and check "Keep weather station in high speed mode". this updates currdata.1st pretty frequently. Catch-22, the currdat file only has the latest reading, not any history.
now, in Weather Display, on its control panel, Station Type tab, on the "ELV/LaCross/....." tab, there's a box to the top right for "Heavy Weather Import/WS2810", and check the 'use currdat.1st for data source' and the 'every 5 second update' boxes. select location for currdat.lst file, and of all the awful places, its in "C:\Documents and Settings\All Users\Application Data" on my XP system. I also check 'use gust data'
don't select any other weather station options (if they are selected, click the 'none selected' at the bottom, close/save, and come back).
now you'll get data every 5 seconds or so.... however. GUST data isn't being processed at present
( weather display is just taking the peak of the average readings, which is not the same as the locally tracked 'gust' value in heavy weather, or on the stations panel.
one downside about this setup (and its the only one I could get working) is that since its not looking at history.dat (and it can't read the history.dat files from the WS281x version of Heavy Weather), if your software is offline for any reason, the data is lost to Weather Display, and Wunderground or whereever you up it to.