John hasn't updated to v1.10 yet, but it has a new feature which is nice for portable app users. Called "Placeholders" you can override the default browser used for URLs in two ways.
On a per-entry basis by modifying the URL:
cmd://{FIREFOX} "http://foo.bar.baz"
As a global override by adding this line to your KeePass.ini:
KeeUrlOverride=cmd://{FIREFOX} "{URL}"
sounds promising!
"What about Love?" - "Overrated. Biochemically no different than eating large quantities of chocolate." - Al Pacino in The Devils Advocate