WordPress MU

I am hoping to use thesis as my theme and to use OpenHook to help customize my blogs, but can't get OpenHook to work site-wide.

I tried to install openhook only in mu-plugins, hoping it would appear site-wide, but no luck. Nothing.

I can activate the openhook plugin through my backend (which puts it in the regular plugins folder) and it will work for the main blog. Even if it is activated site-wide, it only works on the main blog.

This is such an amazing plugin...there has to be a way to make it work.

Any ideas?

You could try asking the plugin author. To be honest I've never heard of it and as you didn't provide a link I've no idea what it does or who wrote it.