On windows: type
>>> zomeinput
Press home key.  In command window (terminal interface), cursor goes to
just before z, where one would want.  In IDLE (2.5.2, 3.0b2), it goes to
beginning of line.  If current patch does not fix this (there is no
mention), would it be easy to add?

I would expect so because the current page up places the cursor 4 chars
to the right of the margin (if there is text not visible above the
window to jump to and if there is text on the line jumped to).  So
PageUp PageDn will sometimes simulate the desired Home behavior.