Well, if anyone else tries to do this vDosPlus-Mac migration, the main stumble was my unfamilarity with the Mac world.
The vDosPlusMac app has to be run from the Applications window--then it doesn't show the list of folders I got trying to run it from Downloads (duh) and goes through a quick setup of configuration options.
Then, clicking into Preferences--which leads to CONFIG.TXT--I realized that we already have a highly customized XY4 version of config.txt.
I typed in the handful of XY settings that look relevant amid all the explanation in the XY version of CONFIG.TXT. Things like LINS = 25, WINDOW = 50 (both also changeable in the vDosPlus-Mac version of CONFIG.TXT), TITLE = XY4, BLINKC = OFF (that blinking cursor was annoying), KEYMODE = 1, WINKEY = OFF and LPT4 = CLIP.
I think one of the last three restored that vital clipboard connection, at least for pasting in from outside apps (via CONTROL-V, not COMMAND-V). Still can't get XY to copy onto the clipboard--the COPY command chooses a line just below what's highlighted--but...it's a good-looking, 90% functional window.
Any hints on copying from XY to the clipboard--some vDos-Mac tweak?--appreciated. This Mac thing might work out after all.
Jon Pareles