I can find a plugin for CS5.5, and for CS6, but not CS5.
Can you post the links for these plugins you found?
As I recall, CS4 required a plugin, and CS5/5.5 introduced
native support for RED media (excluding RED Epic).
CS6 included native support for RED Epic (and maybe others).
If you have RED Epic files, you can transcode them
for use in CS5 using REDCINE-X PRO:
So... does the RED EPIC Importer Plugin for CS5.5 work in CS5 as well?
"Note: This download is only for Adobe Premiere Pro CS5.5,
After Effects CS5.5 and Adobe Media Encoder CS5.5.
The importer has been integrated into the CS6 versions
of the products. Thus there is no need for this plug-in for CS6."
I think that OP can try if CS5.5 RED Importer works in CS5 as well.
Regard to your quote from Adobe Labs webpage, I suppose that's just a warning for some sort of CS6 users meaning, 'Do not hesitate to scroll the webpage down a bit - your RED Importer update is there'.