It appears to be possible to calibrate this meter manually from the front panel and partially (one range at a time), and do the "cold" calibration only, pages 5-17 and 5-18 of the service manual describes the procedure. You would need an accurate source for each calibration point though or a stable adjustable source with a reference meter to get the right value. You don't need any "single trigger signals" if you do a manual calibration from the front panel. If you have a reference resistor, say 100kOhm, you could try to calibrate only 200k range and see what happens.
Cheers
Alex