You can actually just hit the rocks from position 3. Not all, but enough to get through.

Kaia Foglio from Girl Genius used four roller clanks to do this on her playthrough. it's on youtube if you want to watch it, but beware, she's also telling stories of how things got started and such so she rambles, and looses her place a time or two ;)

that is NOT how I did it lmao I complicated it WAY more. cause theres a teeny path where you can do something similar with the two clanks in the first section of the level and get another one to this same area, which allows you to use a spring clank to bounce one much closer to the rocks. except, well, getting a rollerclank from the first section is WAY harder and clumsier and basically requires constant repositioning of the block you can push around

Figured this one in my own first time through and was surprised when the achievement popped up