I found how to import a custom IR command in Integration Designer
Open "Library / IR Library Manager"
Open a cml file, then select a product and a device.
Add a function, put a name on it and then go to Hex View.
Paste your Hex code in this field and then load this function from the Macro Editor windows.

Do not forget to check the "Frequency" and "Minimum repeats" options.

(My frequency is 36.1 Khz and 0 repeat. I know it may change from the device.)

I wish my explication is clear.

For my Marantz I found the code on this page : [Link: us.marantz.com]

See IR code list file (XSL file)

Hope this can help someone :)