Is it possible ? I have brushes using a specific texture and I want to select them all / show only those so I can edit the brushes geom (not replacing the texture). “Find/Replace Texture” is a scam : it can only REPLACE textures >_<*.
EDIT: Also, how do you select all faces from a brush (so after that you can deselect some of the faces you dont wand to edit ?)
Good is making func_group - for example in my map eden_fight I have jungle house made func_group - then you can select this with shift+alt
Faces, triangles you can select with shift+ctrl+alt
You should go through 2-BIT tutorials http://www.pythononline.co.uk/et/tutorial.htm
ctrl-shift dragging mouse hten you can select multiple faces at once, but not what you are really looking for.
What you are looking for doesn’t exist afaik.
The only thing you could do (not an easy solution) Open the map file in notepad or something similar, then use the find / replace function there and adjust the coordinates of the points.
Select a brush with the texture you are looking for, hit shift+ctrl+left mousebutton to select one face of the brush
use shift+a to select all the brushes with that texture
use I to invert (making you select everything else) - the use H to hide them
so…now are all the brushes with your selected texture available for you to abuse 
KIC > thanks for trying, but you misread the question.
Stealth > Well at least you taught me how to select multiple faces at once ! 
Magic > Worked !
Well, to be more precise and for future reference there was a little misexplanation :
To select all brushes using the same texture, you have to select a shader (not the face using that shader) with either middle bouton on that shader painted on a face, or selecting it in the texture browser. Then hit SHIFT+A and give all your love to Magic. <3