In the latest SCI1.1 versions (LSL6, some demos), it is possible to write text to a secondary monochrome monitor.
There is no official support in DOSBox, but there is an unofficial patch, available from
http://www.vogons.org/viewtopic.php?f=32&t=26110&start=20, which adds this. It was a bit of a hassle, but I managed to make it work. Now, using the DbugStr kernel call, you can print any (heap) string to the secondary display.
Another thing that you can do with this (hinted at in the subject line) is that you can turn on a special mode where the Message kernel call will print text strings from an xlate resource (extension trn) on the second monitor as the corresponding strings are fetched from the ordinary message resources. The file formats are identical, except that the first byte is 94 hex rather than 8F hex.
To enable this mode, add the following line to resource.cfg. Note that doing so will bomb you to DOS if some of the XLATE files do not exist.
xlate = .
You can substitute any directory for the dot.