Starting with 1.4 NagVis supports Merlin as a replacement to ndoutils.
Simply set backendtype to merlinmy, the rest of configuration is similar 
to ndoutils.

Here is an example:

; in this example the ID of the Backend is "merlinmy_1" you can define another ID.
[backend_merlinmy_1]
; type of backend - MUST be set
;backendtype="merlinmy"
; hostname for Merlin db
;dbhost="localhost"
; portname for Merlin db
;dbport=3306
; database name for Merlin db
;dbname="merlin"
; username for Merlin db
;dbuser="merlin"
; password for Merlin db
;dbpass="merlin"
; maximum delay of the Merlin Database in seconds
;maxtimewithoutupdate=180
; path to the cgi-bin of this backend
;htmlcgi="/nagios/cgi-bin"