http://www.modaco.com/Scrolling_in_Pocket_IE-t231431.html

[HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Explorer\KeyMaps]
"50"=dword:1
"56"=dword:2

The key name is the keycode you want. 50 = Key 2, and 56 = Key 8.

The values available are:

1 - Page Up
2 - Page Down
3 - Top
4 - Bottom

5 - Horizontal Page Up
6 - Horizontal Page Down
7 - Horizontal Top
8 - Horizontal Down

9 - Default Layout
10 - Desktop Layout
11 - One Column Layout

12 - Full Screen Toggle
13 - Show Pictures Toggle