If you want to deploy a Windows 8 Image with language packs, and want to install .Net 3.5 later, it will fail. As stated on TechNet (http://technet.microsoft.com/subscriptions/hh506443.aspx), mind, that you will have to install .Net 3.5 first:

• Installing a Windows language pack on Windows 8 before installing the .NET Framework 3.5 will cause the .NET Framework 3.5 installation to fail. Install the .NET Framework 3.5 before installing any Windows language packs.

So, when you just took install.wim, and added the language packs, and you will install .Net 3.5 while OSD or as an Package/Application later, it will fail.
To avoid this, just take the install.wim file from the Windows 8 DVD, and mount it with dism:
dism /Mount-wim /wimfile:"<Path to install.wim>" /mountdir:"<Patch to Scratch Directory>" /index:1

After this step, you can enable the .Net 3.5 Feature with this dism command:
dism /Image:"<Patch to Scratch Directory>" /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:"<Path to SXS Directory>"
You will need to provide the location of the SXS (Side-by-Side) Folder, this folder reside in the “<Windows 8 DVD>Source” Directory

And after that, you can Import your language packs:
dism /Image:"<Patch to Scratch Directory>" /Add-Package /PackagePath:<Path to your lp.cab>

You can now import more languages or enable other Features. When you are finished, close the wim file, and commit the changes. If you don’t want to commit, use the /discard switch instead of /commit:
dism /Unmount-wim /MountDir:"<Patch to Scratch Directory>" /commit