"At this time, RockMelt is only compatible with Intel Macs OS X 10. 5 or higher, Windows Xp, Vista, or Windows 7." - http://help.rockmelt.com/customer/portal/articles/9226
I cannot find a link to download any version from rockmelt.com.
0.16.91.483 is the latest version that I could find (from softpedia) and it will not run on Wine.