Consider using a Copy File command to put the config.xml file in a full path, then reference that full path in your Install Command.
e.g. Copy File config.xml to C:\downloads\Altiris\Office 2007 Enterprise\Standard.WW\config.xml
Execute managed software delivery as above, modifying command line for full path:
"Office 2007 Enterprise\setup.exe" /config "C:\downloads\Altiris\Office 2007 Enterprise\Standard.WW\config.xml" /adminfile "Office 2007 Enterprise\MyUpdates\Office2007-STD.MSP"
Does this resolve the issue?