Generally Sitefinity supports News Indexing. You can create a new index and specify your start point or a certain page you want to be indexed.
If you want to index only certain controls on a page you should modify ~/App_Data/Search/[NAME_OF THE _INDEX]/fieldsInfoProvider.xml. In this file you can set weight to all fields you want to search.
name = some name
weight = -1 will not be indexed
weight = 1 will be indexed
filterTag = we are getting the div of the control
filterAttributes - we are getting the ID ot the div
Using filterTag and filterAttributes will allow you to include or exclude some controls
from the search results.
Also each page has Searchable property that can also be used.
the Telerik team