DOSPRN will capture the LPT output of NTVDM (not vDos!), but probably will also be able to print an ASCII text file directly.
vDos always creates two text files: #LPT/COMx.asc (ASCII) and #LPT/COMx.txt (Unicode) in its working directory.
Setting LPT1=DUMMY in config.txt will instruct vDos to perform no further action when those are created.
So look for #lpt1.asc and feed that to DOSPRN.
If DOSPRN has an option to print a file directly use something like:
LPT1=\path\dosprn.exe c:\vDos\#LPT1.asc.
You can't print directly from DOSBox, but you can use a utility program (for example, Notepad) to print the WB1, WB2, or WB3 files the W&B program writes to your harddrive. However, a more convenient solution is to install DOSPRN (www.dosprn.com) along with DOSBox. Make the following additional configuration file changes to use DOSPRN: