Lasors states that if you wish to be tested in a twin you must be trained so that in a simluated IMC you can maintain stable flight after an engine failure at climb power then climb at the recommended speed and carry out normal fligth manouevres under assymmetric conditions.
http://www.caa.co.uk/docs/33/LASORS2005.PDF
As you are already a holder of an IMC rating I believe you are required to complete your next IMC renewal in a twin. Even if it is not a requirement it is certainly highly advisable to undertake some IMC M/E training before exercising the priviledges of it in a twin.