Templating custom fields

[Menace]

I'm using related products custom field. In the frontend related products are displayed on the productdetails site below the main product just like I want. So far everything is fine.
By default the customfield displays just the related products image and the description.

Now I want to add the related products price and manufacturer to this field.

How can this be done?
And even more important: what file has to be changed to alter this custom fields view?