In order to compile scannedonly you need the samba source code installed, 
as well as libclamav development files. You need not only to unpack the 
samba source code, but also run ./configure and make (although the first 
10 seconds of make will probably do).

After that, configure the scannedonly source:
./configure --with-samba-source=/usr/src/samba-3.0.26a/source/ --with-samba-vfs-dir=/usr/local/samba/lib/vfs/

and run make 

and (as root) make install. 

