First of all, the versions in CVS head are not supposed to work, this a merely an exchange area for developers (aka kitchen sink).
The versions which are supposed to work are releases, or versions close to releases (e.g. in CVS oacs-5-2)
In general, there is no need to unmount etc. the packages.
what i do is rougly the following:
once:
a) get a full tree of oacs from HEAD
b) get a full tree of oacs-5-2
then decide, what you want to use from where.
i have a tree, where everything is from oacs-5-2, only xowiki is a link to the HEAD version.
in order to updgrade, you
1) do in the approproate package a cvs .... update
2) do acs-admin/apm/ a "Install packages" and click on the updgrades
and you are done.
-gustaf
PS: xowiki has a import/export facility, such you can export all your pages to a ascii file and import these afterwards again, also in a different installation. currently, one uses the category associations, since one cannot export the category trees and their associations, but the export is certainly helping here.
PPS: The full-release circles or CVS updates are IMHO not the right tool for a someone starting with oacs, or someone trying new packages to proceed. the idea of the .apm files was addressing this problem, but these are not very popular (not used?)
