You need windows 7 to install RockMelt on linux.
first download & install RockMelt in to windows 7.
Download RockMelt from here:
http://www.rockmelt.com/post-download_win.html
After instaling RockMelt in to windows
Go to your Computer > Users > YOUR ACCOUNT > Local
copy RockMelt (folder) to pendrive or other portable device
Now install winehq to your linux computer.
Download winehq from here:
http://www.winehq.org/download/
ubuntu:
go to Aplications > Wine > Browse C: drive > Users > YOUR ACCOUNT NAME > Application Data
& copy RockMelt (folder) to there.