I did a kernel build in N900 (3h + 3/4 battery).

To do it I had install:

gcc-4.2-base
cpp-4.2
libgomp1
libgcc
gcc-4.2
libgtk2.0-bin
gcc
binutils
linux-kernel-headers
libc6-dev
cpp
make
kernel-source

Some of it is not needed actually, but I don't remember which one (or two, or three...)

You may have a problem with root FS space. I work with root on 32GB /home.

EDIT: For C++ - don't forget about libstdc++6 and "-dev" version.