Hello,
The very interesting note 2232191 solved my problem. 
I did not follow the note exactly, I did a parallel installation with original one.
The key factor is in this file (for Tomcat 7)
C:\Program Files (x86)\SAP BusinessObjects\SAP BusinessObjects Enterprise XI 4.0\wdeploy\conf\config.tomcat7
This line is crucial:
as_dir=C:\Program Files\apache-tomcat-7.0.67
since it appears that wdeploy needs to read some files from Tomcat tree.
I used predeployall argument and copied webapp files manually to new Tomcat tree.
Good luck and keep your Tomcat server up to date !
Crackers hidden in darkness are watching your servers... 
Regards,
Stéphane.