So, my way would be to use Data groups. Not sure if this is the "best" way though. Most likely a better way than a v long irule.
So create a Datagroup with all your redirects called redir_dg (for example):
/aboutus/ContactUs/index.html := /en/about/contact
etc.....
And then refer to this datagroup in an irule:
when HTTP_REQUEST {
if { [class match [string tolower [HTTP::uri]] starts_with redir_dg] } {
HTTP::redirect http://[HTTP::host][class match -value [string tolower [HTTP::uri]] starts_with redir_dg]
}
}
Hope that helps. I'm sure better iRules than I will think of a better way but it might get you started.
N