You should never have to apologise for making an on-topic reply to an older thread. Community Central should be a more welcoming place, instead of making users feel they have to apologise for asking a relevant question.
When you say, "hover over an icon", I'm going to assume you're talking about a user icon, AKA avatar, in which case the answer to your question is:
.avatar:hover {
cursor:crosshair !important;
}
However, I'm slightly confused by your statement that it defaults to cursor:help - because it doesn't for me, so perhaps you're talking about something different.
In any case, here's how to determine the relevant selectors for any element:
- Right click on the element you're interested in
- Choose "Inspect element" (Or something similar, depending on browser)
- In the browser inspector that opens, the current element in the HTML source will be highlighted.
- In the case of a user avatar, it is made up of several parts: a link with an image inside the link. In this case it's sufficient to apply the cursor to the image, but keep this in mind for other cases.
- On the left is a list of CSS rules which apply to the highlighted element - from these, you should be able to determine the relevant selector.
- In the case of a user avatar, the first selector listed is "#Wall.Thread .avatar", but it is sufficient to just use the class ".avatar", so that it will apply to all avatars, not just avatars in wall threads.