Hello dann23, first of all, welcome at the win2008workstation forum!
Copying onlineidcpl.dll from %SystemRoot%\System32 and %SystemRoot%\SysWOW64 and onlineidcpl.dll.mui from %SystemRoot%\System32\en-US and %SystemRoot%\SysWOW64\en-US is indeed a good start.
After copying the files, running regsvr32.exe with as parameter the dlls should be the next step. However, after registering it still doesn't show up in the Control Panel.
A search through the registry for "OnLineIDCpl.dll" reveals several keys in which the dll is listed. These should possibly also be copied, but after copying I still couldn't get it working...
One thing you could try is to invoke the command control /name Microsoft.UserAccounts /page pageOnlineAccounts
in both Windows 7 and Windows Server 2008 R2 while running the Sysinternals Process Monitor
tool in the background. This allows you to compare the registry keys and files accessed during the load of the Online IDs page in the Control Panel.
Hope this helps you!
Please report back if you are making progress or even get it working!