Cisco Firewall :: ASA 5520 Active / Standby Remote Software Update

We have a pair of 5510s and a pair of 5520s, each in Active/Standby mode.  I'd like to upgrade the ASDM and ASA software on these, but am finding no documentation that advises on how this can be done without physical access to the devices.  It so happens I am on site, but we will be deploying these throughout our network and I'd like to be able to perform this type of maintenance without travelling to each site.  We utilize CSM and ASDM to manage these for the most part, but are certainly capable of configuring via CLI. 
 
The issue may be my lack understanding of the ASA fundamentals, but I don't really get how the software can be copied to the individual ASAs of the pair so they may be reloaded and upgraded without outage. With a remote SSH connection to the pair, I'm only copying the software to the Active ASA, correct?  Or is there a way to get the software to each disk individually from the single SSH connection?  I'm not quite sure how to manage the Standby ASA without consoling into it... If I can indeed remotely get the software to each ASA (copying to different disks?? i.e. disk0: and disk1:?), then I also run into an issue updating the boot statement for each of them individually, though to resolve that I suppose I could just remove the old software, but that seems like bad practice before confirming the new software is ok.If there is a simpler way of deploying new code via ASDM or CSM, I'm certainly open to that.