I assume that your listbox has a MultiSelect set to 1 or 2 (multi or extended
instead of single).
assign a macro to your print  button.
use something like:
For i = 0 To userform1.listbox1.listcount
If userform1.ListBox1.Selected(i) = True Then
' Record a macro that calls up a excel document, then print the entire
workbook.
' use this macro as a template to insert here and substitute the selected  file
name from the listbox
End If
Next i

do you need more explicit ideas?
hope this helps.