The fundamental problem I'm struggling with is that Force.com platform doesn't allow adding a lookup field related to Event/Task on a custom object or vice versa. I need to have a related list section on Event page and display the records of a related custom object, so I've been playing with this idea-

- Create a text field to represent Event ID, in my custom object. Manage the relationship with Event through this field in custom controller/extension classe.

- Create a visualforce page mimicking all the functionality of the standard Event page and then add a pageBlock for the related list. I need to create pages for both edit and view functions. I'm assuming this is doable, although very painful. Pls point out if I'm wrong with this whole idea. 

Assuming it works out as planned, here's a problem I see already- I can have a button (say on Opportunity page/Open Activities section) to open a new Event in my visualforce page in edit mode and have the record created. Once a record is created, it will show up in the list in "Open Activities" section. Now if I click on this record or the Edit link next to it, the record is not going to open in my visualforce page. It will probably open up in the native page layout thats associated with the record type... that doesn't serve the purpose. 

I don't want to override the standard buttons/links because I have a bunch of other record types that use different native page layouts. Is it possible to tie up certain record types to always use my visualforce page, i.e., override the standard buttons/links based on record types? If not, what other options I have?

Any help is much appreciated. Thanks in advance.

Vas