requesting a version bump for liferea to 1.02. According to release notes this fixes several problems including compiling agains Firefox 1.5
There is a new version 10 (1.03) so maybe 1.02 should be skipped.
Compiling against firefox 1.5 was integrated in the 1.0-r1 ebuild. However other very useful things were fixed, including a fix to URLs with commas in it (when you want to open the article in firefox). Removing the src_unpack from 1.0-r1 ebuild (and renaming it to 1.0.3) did the job for me
Just one more success report in case it helps: I'm using liferea-1.0.3 compiled against Firefox-1.5 since yesterday, and it works fine (~x86 here). My ebuild was similar to what Bernard describes (1.0-r1, minus the "src_unpack" and the "eutils" on "inherit").
liferea-1.0.3 has been just been commited to the tree, sorry for the delay!