I'll show you how to do ABH in Portal with scripts
To start this download: http://www.autohotkey.com/ after AutoHotKey create a new script on the desktop and write in this: * space ::
Loop
{
GetKeyState, state, space, P
if state = U
break
Send, {space}
Sleep, 20
}
return
save after right click on it and click Run Script go to Steam and launch Portal and start new map you want to try. HAVE FUN !! :)