I am posting this for future reference since it took me a while to resolve and the information was not already out here.
Today I was trying to install the trial version of easyphpcalendar v6 on Powweb.
The compatibility tester program initially returned two errors, one on the "Sessions" test (failed) and one on the "Zend Optimizer" (not found).
Both problems were resolved by adding the following lines to php.ini:
zend_extension = /usr/local/lib/ioncube/ioncube_loader_lin_5.2.so
For those who do not know how to find php.ini, in the current incarnation of Powweb's control panel:
1 - Log in to Ops.
2 - In the "Scripting & Add-ons" section, select "CGI and Scripted Language Support".
3 - Select "PHP Scripting".
4 - Scroll down a bit.
5 - Click "Set" to select your default PHP version (5).
6 - In the edit box below, make your additions to php.ini and then click Save. The new lines can be added at the very bottom.
Immediately after saving the changes the compatibility script ran with success (Pass) on every test.
This information was also not found in Powweb's knowledgebase for some reason. I did a chat session with a good support person and she fixed my php.ini for me, then I went in and looked at what she changed and posted it here. Perhaps it will save someone the hassle I went through.
I don't know if the full product works but I was able to run the self-install exe successfully and the setup script that launched automatically seemed to work.