Don't assume that BETA 4.0 is better just because the number is larger.
What problems are you having with 3.3 that make you want to upgrade? If you explain what's happening, perhaps there's a work-around.
If you insist on trying it, Page 9 of the Wholehog II handbook has the software upgrade instructions.
I don't have the list of known problems with 4.0 (Brad might have a copy sitting around), but we don't consider it reliable enough to use on shows.
As I recall, the major change in 4.0 were partial support for talkback (which only works with specific fixtures) and curve editor. www.flyingpig.com/support/hog2/manuals/updates.shtml
V4.0 should NOT be used for live productions. It has been moved to the archive site primarily for the purpose of providing access to the talkback for EC-2. It is NOT show safe. v3.3 is the only supported version.