Here is a tip from mgc@cray.com (M. G. Christenson).

Look at /usr/include/X11/cursorfont.h for a list of available cursors.
You can use the names in there by removing the `XC_`.  

Here`s a little proc I use to make my entire application go `busy`
while it`s doing something. Just call it with the commands you want to
execute, and the watch cursor will be displayed for the time it takes
the commands to complete.  Note that any new windows will have their
normal cursor.

proc busy {cmds} {
    global errorInfo

    set busy {.app .root}
    set list [winfo children .]
    while {$list != ""} {
	set next {}
	foreach w $list {
	    set class [winfo class $w]
	    set cursor [lindex [$w config -cursor] 4]
	    if {[winfo toplevel $w] == $w || $cursor != ""} {
		lappend busy [list $w $cursor]
	    }
	    set next [concat $next [winfo children $w]]
	}
	set list $next
    }

    foreach w $busy {
	catch {[lindex $w 0] config -cursor watch}
    }

    update idletasks

    set error [catch {uplevel eval [list $cmds]} result]
    set ei $errorInfo

    foreach w $busy {
	catch {[lindex $w 0] config -cursor [lindex $w 1]}
    }

    if $error {
	error $result $ei
    } else {
	return $result
    }
}