Is it sad that I have an original VT-102 video terminal user's guide
sitting just a few feet from my desk?  Probably, but it's one of those
manuals from the olden days that included all the escape sequences, and
according to it, the ANSI control sequence to turn on smooth scrolling is:

        ESC [ ? 4 h

and to return to jump scroll is

        ESC [ ? 4 l

(that's a lower-case l at the end of the second one).  The support was
quite standard on DEC and Wyse terminals (the Wyse also supported
something like shift with the up and down arrow to change rates), but I
don't recall ever seeing a terminal emulator that actually supports these
codes or that particular feature.

Chris Zagar
Estrella Mountain Community College