How to obtain current-voltage trace using a picoammeter?
My old Keithley picoammeter had a 'recorder' output (analog) that
could be sent to a motorized chart recorder.   An X-Y recorder
(or the A/D converter/computer/printer equivalent) with
test voltage sensed by the 'X' channel can do the same.

Your chosen
deviceKeithley 486 (see Fig 3-14) has analog outputs,  but also autoswitches
the gain.   You'll have to note the gain range, and maybe
disable gain-switching.

With suitable digital hardware (to address the IEEE-488 port)
you might skip the analog output connection, but be aware that not all
digital outputs are timely (and you want to ensure somehow
that your V and I signals don't get different delays).