More script

I was reading Nick’s blog the other day and noticed he has the simple open/close more on his site. After asking him for the code, I tried it on WP 1.0 and it won’t work. (thank goodness for backups!)
So, I went to Scripty Goddess and found what they use on MT.
Any way to hack it for all of the WP versions?
Nick’s code only works for 1.01, which is disappointing to me as I don’t want to upgrade just yet.