Tested with CXOffice 5.0.3 on slackware linux. I used the version downloadable from grants.gov, plus the update package from the same source.
IE6 must be installed in a win98 bottle (I also have Office 2000 in there but I doubt this is necessary). What seemed to work best was to open the installer file directly via IE (that is, when it downloads, just open the .exe file); I didn't have much luck using the Cxoffice install feature and like a dummy, forgot to note down the error messages. (Will do this soon).
If you intend to use the email features in PureEdge viewer, be sure to install Outlook Express (which you can do at the same time you install IE).
After verifying that the application will start, install the update. The grants.gov files are here: http://www.grants.gov/resources/download_software.jsp
Be sure you apply the update as there's a major bug in the submission agent of the original version.
Note that I've only opened, edited and saved files with PureEdge viewer. I haven't tried to submit anything yet. It renders a little slower than I'd like, especially if you scroll up and down really fast, but it seems to be solid enough to work with.
The browser plugin gives errors and won't open files, however. I'm going to keep playing with it but for now the best thing is to download the file straight to your computer, run pureedge directly, and manually select the file.