[ck2]

How exactly would you use this with third party code executing on the server that cannot be modified?

eaccelerator's session handler (was) simply built in and requires no modification, just add the one-word setting to your php.ini

[maratd]

You can't modify your code, but you can modify your php.ini?

OK.

PHP has a very nice feature where you can automatically prepend (and append, if you want) a file to all requests. Create a single file, modify your php.ini, done.

I am not telling you that eaccelerator isn't amazing. I am showing you how to get around problems you may run into if you end up using a different op-code cache.