[Zope] Structured Text

Hi, Does somebody has experience with modifying STX in such a way that it only effects some parts of the Zope Tree? ie. I'm looking for a way to make STX showing pictures (I managed that), but I want to make it so that all pictures have the same width and height (independend on the real height/width of the picture) and a link when clicked on the image so that the full image can be shown.... I've looked for all the information I could get, but unfortunately it looks like I miss some skills here. My question: is there somebody who can give me a direction, hint, .... etc? Thanks, Tom.