Progress was made, now stalled, might restart
After a few dead ends (notably the plotter approach), I settled on:
Run s1.exe in '
DOSBox' under Windows (XP, currently)
Use the Data Export from s1.exe to produce a .DAT file from a TST
Use
GNUPlot to plot the raw .DAT data (to GIF, PNG, PDF).
The tool (which runs in XP) analyses the DAT data (eg extract labels, data types, maxima/minima...), deals with some quirks that confuse GNUPlot (eg writing '2.45299747e-007' instead of '0'

) and then composes an executes a GNUPlot command file (in XP).
Proof of Concept output attached.
The parser and GNUPlot bits are basically done (VBScript

). Main remaining tasks:
1. Automate .TST file handling.
While developing, I used manually-exported DAT files, but they don't contain test type, comments, bounds, etc from the TST file. One may want these as well (to accompany the nice graph) but this is a manual operation at present. Automating this will require creating some S1 Procedures, then running s1.exe-within-DOSBox to call the .PRO, spit out a text file with the test metadata, then the .DAT file, and then return to Windows to create the graph.
2. Deal with some bugs in handling multiple dataset overlays.
3. Testing and documentation
4. Nice to have: some kind of GUI, with thumbnails, palette choices, etc. This will probably be an
HTA, which - as it's basically an HTML page - doesn't need compiling, and exposes tinkerable source. This might not work with latest IE versions, though...
Development has - ahem - stalled

, but with winter approaching I might actually finish it. That said, I'm doing the work for someone specific, and would have to check if he'd be happy to share it (not a prob for me).
That was longer than intended - let me know if interested, it might spur me on!
autopoiesis