http://lotronline.decipher.com/download/ is where you can get the card manager.
After you have installed the Online card manager, there is a shortcut on your desktop. Right click on the shortcut and select Properties. In the Target box, put in
"C:\Program Files\Decipher\
The Lord of the Rings TCG 2\LotROTCG\LotROTCG.exe"
if you used the default installation directory. If you changed the directory during the install, you need to click the Find Target ... button on the Properties window and select the LotROTCG.exe file.
Don't get this file confused with "The LotR Online TCG.exe" file, as this is the one that looks for stuff online and will go away soon-ish.
Click OK and you should be good to go with the desktop icon, it should start up without the online checks.