Two conditions, one for x86 and one for x64. I'll share our x86 condition and scripts here:
Step 1:
REM Kills Outlook
\\Server\Share\pskill.exe outlook.exe
cls
Step 2 (Run this as a service account, not as the SYSTEM user):
REM Installs MS Office Online Sign-In Assistant
msiexec.exe /I \\Server\Share\Microsoft\Lync\OnlineServices\SignInAssistant\7.250.4259.0\x86\msoidcli.msi /qb! ALLUSERS=1
Step 3 (Run this as a service account, not as the SYSTEM user):
REM Installs Lync Online Client
\\Server\Share\Microsoft\Lync\2010\4.0.7577.280\x86\LyncSetup.exe /Install /Silent