This can be done in Chapter 3. The Epsilon spot is at 45,12.
Go to 45,12. The Epsilon icon is in the upper left corner. Walk all the way up the diagonal wall and climb the small wall on your right. Now turn into a ball (X) and use your speed boost (R1). You'll want to hit the diagonal wall in the right angle to bounce right to Epsilon.
Credit to:
http://www.ps3trophies.org/game/knytt-underground/guide/ and k1ll1ng5pr33
Credit to Mr Vuule for the video