[c-nsp] SCP router-to-router work?

[Raymond, Steven]

So I can easily scp an image from my workstation onto a router.  But I
cannot seem to scp IOS files between routers (sup720s, SRB2 code).  Am
99% certain I did so in the past, but no amount of monkeying could get
it to work recently.  Failure indication varies (it happens
immediately), but it usually reports permission denied or file not
found.  The target media was either disk0: or sup-bootdisk: .  Tried all
manner of path permutations.  

Has anyone got a working CLI example that works?

Thanks!