Docs can be found at http://incrtcl.sourceforge.net/iwidgets/iwidgets/scrolledtext.html and http://purl.org/tcl/home/man/iwidgets3.0/scrolledtext.n.html
Marty Backe's example of displaying a file in a text widget:
package require Iwidgets iwidgets::scrolledtext .t pack .t -fill both -expand true .t import $filename end
Category Command, a part of incr Widgets