We ended up using a custom analyer based on the SnowballAnalyzer
public class CustomAnalyzer : SnowballAnalyzer
{
public CustomAnalyzer() : base("French") { }
public override TokenStream TokenStream(string fieldName, TextReader reader)
{
TokenStream result = base.TokenStream(fieldName, reader);
result = new ISOLatin1AccentFilter(result);
return result;
}
}