Login again in your hacked nslu2 Install needed package:
# ipkg install ppp openvpn chat openntpd
# ipkg install http://downloads.openwrt.org/snapshots/ixp4xx/packages/hwclock_2.13.0.1-2_armeb.ipk
And let configure them:
# vi /etc/ntpd.conf
server 193.204.114.232 server 193.204.114.233 server ntp1.inrim.it # or a ntp server near you server ntp2.inrim.it # or another ntp server near you listen on *
# /etc/init.d/ntpd […]