SqueezeCenter employs a keep alive mechanism, closing HTTP connections after 75s.  There are a few exceptions to this, (for example Jive firmware downloads), although not for the softsqueeze binaries.  Hence, when installing softsqueeze over a limited bandwidth connection, the download stops after ~75s, and the installer reports a corrupted download.  This can clearly be worked around by setting a sufficiently long timeout, but the correct solution would seem to be:

a) Add further exceptions for SoftSqueeze binaries

or

b) Reset the timeout timer whenever data is successfully sent or received.