Yes there is. What I will describe uses adb, but you can adjust for using a terminal on your phone if you wish. Grab the busybox binary from somewhere, I think I have it in .zip form in my collection, extract it, put just the binary on your sdcard. Then using adb use the following commands:
Code:
su
mount -o remount,rw -t yaff2 /dev/block/mtdblock4 /system
mkdir /system/xbin
cd /system/xbin
cp /sdcard/busybox /system/xbin/busybox
chmod 0755 busybox
busybox --install .
mount -o remount,ro -t yaffs2 /dev/block/mtdblock4 /system
sync
reboot
good luck