Unsure if this is what you want to do, but have you tried the Take Snapshot option to Retrieve binary configuration?

Some time ago, we had a similar user request, they wanted us to get the binary config and when they needed it, they'd download it and it'd be in UCS format.  

I don't recall the specifics, but we needed at least one driver HF, maybe two....but again, this was years back, so I'd think that now, it'd not need HFs (as long as you were reasonably current).  

But, the take snapshot task (with the option checked) will do the command you mentioned:

b>Receive:</b> save /sys ucs /var/local/ucs/HP_NA_F5_CONFIG

Saving active configuration...

Expect: [-re SI\_NAM\_0000\_P\_005\@\(f5_h0stname\)\(cfg\-sync Standalone\)\(\/S1\-green\-P\:\:Active\)\(\/Com \rmon\)\(tmos\)\#]

Receive: configuration...
/var/local/ucs/HP_NA_F5_CONFIG.ucs is saved.

NA_ID_goes_here@(f5_h0stname)(cfg-sync Standalone)(/S1-green-P::Active)(/Com mon)(tmos)# <br/><h4>Retrieving /var/local/ucs/HP_NA_F5_CONFIG.ucs via SCP</h4><br/><b>SCP</b> connect to na_IP:22 <br/> - Succeeded.

<br/>Getting /var/local/ucs/HP_NA_F5_CONFIG.ucs

- Succeeded.

If you're looking to automate the downloading of the file, check out the API command:

download binaryConfig

I've not tried this API command, but looking at the docs, think this would let you create a script that'd download / export the file that NA captured from the take snapshot task.  

Hope  this helps,

Chris