[gentoo-user] out of disk space to compile webkit-gtk

[Joseph]

I'm upgrading the system and running out of disk space to compile webkit-gtk

* Checking for at least 18 gigabytes disk space at "/var/tmp/portage/net-libs/webkit-gtk-2.0.4/temp" ...                                                              
[ !! ]
 * There is NOT at least 18 gigabytes disk space at "/var/tmp/portage/net-libs/webkit-gtk-2.0.4/temp"

df -h
Filesystem      Size  Used Avail Use% Mounted on
rootfs           28G   16G   11G  61% /
/dev/root        28G   16G   11G  61% /
tmpfs           506M  540K  505M   1% /run
udev             10M     0   10M   0% /dev
shm             506M     0  506M   0% /dev/shm
/dev/hda4        84G   51G   29G  65% /home

How do I tell the system to use /home partition to use for compiling temp tiles?

-- 
Joseph