Based on
http://article.gmane.org/gmane.editors.wily/270
http://article.gmane.org/gmane.editors.wily/271

diff -Naur wily-0.13.42/libXg/gwin.c wily-0.13.42-scrollwheel/libXg/gwin.c
--- wily-0.13.42/libXg/gwin.c	2005-11-05 20:09:07.000000000 +0100
+++ wily-0.13.42-scrollwheel/libXg/gwin.c	2011-03-20 19:51:14.303669715 +0100
@@ -371,6 +371,8 @@
 		case 1:	s |= Button1Mask; break;
 		case 2:	s |= Button2Mask; break;
 		case 3:	s |= Button3Mask; break;
+		case 4:	s |= Button4Mask; break;
+		case 5:	s |= Button5Mask; break;		
 		}
 		break;
 	case ButtonRelease:
@@ -383,6 +385,8 @@
 		case 1:	s &= ~Button1Mask; break;
 		case 2:	s &= ~Button2Mask; break;
 		case 3:	s &= ~Button3Mask; break;
+		case 4:	s &= ~Button4Mask; break;
+		case 5:	s &= ~Button5Mask; break;
 		}
 		break;
 	case MotionNotify:
@@ -399,6 +403,9 @@
 	if(s & Button1Mask) m.buttons |= 1;
 	if(s & Button2Mask) m.buttons |= 2;
 	if(s & Button3Mask) m.buttons |= 4;
+	if(s & Button4Mask) m.buttons |= 8;
+	if(s & Button5Mask) m.buttons |= 16;
+	
 	f = ((GwinWidget)w)->gwin.gotmouse;
 	if(f)
 		(*f)(&m);
diff -Naur wily-0.13.42/wily/const.h wily-0.13.42-scrollwheel/wily/const.h
--- wily-0.13.42/wily/const.h	2005-11-05 20:09:07.000000000 +0100
+++ wily-0.13.42-scrollwheel/wily/const.h	2011-03-20 19:52:00.803019670 +0100
@@ -27,7 +27,7 @@
 	INSET = 4,
 
 	/* mouse buttons */
-	LEFT =1, MIDDLE=2, RIGHT=4,	
+	LEFT =1, MIDDLE=2, RIGHT=4, UP=8, DOWN=16,
 
 	/* keys */
 	Backspace =	0x7f,
diff -Naur wily-0.13.42/wily/mouse.c wily-0.13.42-scrollwheel/wily/mouse.c
--- wily-0.13.42/wily/mouse.c	2005-11-05 20:09:07.000000000 +0100
+++ wily-0.13.42-scrollwheel/wily/mouse.c	2011-03-20 19:57:04.458774672 +0100
@@ -151,6 +151,18 @@
 		} else {
 			b2(v,r,false);
 		}
+	} else if (oldbuttons & UP) {
+		if (m->buttons) /* cancelled an UP */
+			while (m->buttons)
+				*m = emouse();
+		else
+			view_linesdown(v,1,false);
+	} else if (oldbuttons & DOWN) {
+		if (m->buttons) /* cancelled a DOWN */
+			while (m->buttons)
+				*m = emouse();
+		else
+			view_linesdown(v,1,true);
 	} else {
 		assert((oldbuttons&RIGHT));
 		if(m->buttons)	/* cancelled a b3 */
diff -Naur wily-0.13.42/wily/vshow.c wily-0.13.42-scrollwheel/wily/vshow.c
--- wily-0.13.42/wily/vshow.c	2005-11-05 20:09:07.000000000 +0100
+++ wily-0.13.42-scrollwheel/wily/vshow.c	2011-03-20 19:57:55.701391654 +0100
@@ -184,6 +184,12 @@
 		n = back_height(v->t, v->visible.p0,  v->f.font, Dx(v->f.r), m->xy.y - v->f.r.min.y);
 		view_set(v, n);
 		break;
+	case UP:
+		view_linesdown(v, 1, false);
+		break;
+	case DOWN:
+		view_linesdown(v, 1, true);
+		break;
 	default:
 		runepos = (text_length(v->t) * y) / Dy(v->f.r);
 		n = text_startOfLine(v->t, runepos);