Although text searches are not directly integrated into selection projects, the search results can be highlighted in the selection project results list by adding the records to the Favorites list. In the search results pane, select the records to include, right click a record name and select Add to favorites. The records will be highlighted with a star icon wherever they appear, including in the selection project results list.
To filter records based on search results, you need to create a custom subset from your favorites. In the Selection Project panel, click on Custom: Define your own subset... in the Select From menu. In the Custom Subset dialog, click on from the Initial subset menu.
Note, to clear your list of favorites, click on Tools > Favorites > Clear.