Hi,
How many Firewalls do you that you want to use this on. You could:
1) Create a copy of the ASA Device Template and Modify the Download Config Command for the commands you want. Then under the nodes with multiple contexts you could change the Device Template they use to the new one. This would allow you to use the same NCM job.
2) You could also insert the commands you want as a new command in the same device template. For example, add: <Command Name="MultiContextDownloadConfig<Command Name="DownloadConfig" Value="more system:running"/>" Value="ENTER COMMANDS HERE"/> into your existing device template. Now in NCM Settings create a new config type called "MultiContextDownloadConfig". Then create a job that downloads this config from the relevant nodes.
These are a few ways you could do it off the top of my head, if I think of others I will post again. does that help?