Referencing objects late-bound (Doing plug-ins here!)

I'm coding an extensible program. I've designed the required
interface for the ActiveX server to communicate with the ActiveX
client.
So now people write plug-ins for my program and they implement
my designed interface, then compiled as ActiveX DLL.

Now I've a folder for which the plug-ins are put.
When my program starts, it'll check this folder and reference all
the compatible plug-ins.

Now, how'd I go about referencing all these plug-ins?

I know I can CreateObject them through their classname
by requiring them to write their classname to registry.

But is there any alternative here without requiring registry writing
or whatever? Basically they just drop in the plug-in in to that
folder and my program will run that plug-in.

Thx a lot!;)