MS Outlook plugin development

[AldoE]

Hi
I want to develop a plugin for Microsoft Outlook (2003 and following versions).
I know there is a shareware collection of VCL available but that's really too expensive for my budget, so I'm starting from scratch.
I need a kickstarter advice from someone who's already been down that path:
-usefuls "how to"s ...
-best practices
-documentation / websites
-code samples would be great!

I already have the main code working ad a VBA macro inside OL, and I'll be fine to port it to pascal, but I'd like to make it an external, self contained plugin, with installer and all bell&whistles.

The plugin will hook the reply-to-all and item-send events, and then pop-up some alerts based on some cross check between recipient list and message body.

Update: I've already looked at the "Office Automation" Wiki's page, something useful about accessing OL data & objects from within Lazarus, but nothing about plugin building.

Thanks