idv -help
        -help  (this message)
        -properties  <property file>
        -installplugin  <plugin jar file to install>
        -plugin  <plugin jar file, directory, url for this run>
        -noplugins  Don't load plugins
        -cleardefault  (Clear the default bundle)
        -nodefault  (Don't read in the default bundle file)
        -default  <.xidv file>
        -bundle  <bundle file or url>
        -oneinstanceport  <port number> (Check if another version of the IDV is running. If so pass command line arguments to it and shutdown)
        -nopref  (Don't read in the user preferences)
        -userpath  <user directory to use>
        -sitepath  <url path to find site resources>
        -nogui  (Don't show the main window gui)
        -data  <data source> (Load the data source)
        -display  <parameter> <display>
        -islinteractive  <run the isl file in interactive mode
        scriptfile.isl  (Run the IDV script in batch mode)
        -image  <image file name> (create a jpeg image and then exit)
        -movie  <movie file name> (create a quicktime movie and then exit)
        -imageserver  <port number or .properties file> (run the IDV in image generation server mode. Support http requests on the given port)
        -Dpropertyname=value  (Define the property value)
        -catalog  <url to a chooser catalog>
        -connect  <collaboration hostname to connect to>
        -server  (Should the IDV run in collaboration server mode)
        -port  <Port number collaboration server should listen on>
        -chooser  (show the data chooser on start up) 
        -printjnlp  (Print out any embedded bundles from jnlp files)
        -setfiles  <datasource pattern> <semi-colon delimited list of files> (Use the list of files for the bundled datasource)
        -currenttime  <dttm> (Override current time for ISL processing)
        -listresources  <list out the resource types
        -debug  (Turn on debug print)
        -debugmessages  (Turn on language pack debug)
        -recordmessages  <Language pack file to write missing entries to>
        -trace  (Print out trace messages)
        -traceonly  <trace pattern> (Print out trace messages that match the pattern)

You can add in a "type:" prefix to the argument that will specify the type with:

idv -data type:somedatatype:the_file_or_url_to_the_data

Unidata's Integrated Data Viewer > Miscellaneous