I don't think the Accord 15" alloys will fit on the 2.2 diesel tourer front wheels because (I think) they have 300mm brake discs. The 15" will only fit the 2.0i petrol where the front and rear discs are 280mm.
You could use a 16" as a spare, you would probably have issues squeezing 17" wheels into the space for the spare wheel - there was a thread on that. You just need to maintain the same radius, accord alloy wheels do pop up on ebay or on here.
The correct space saver should fit and work fine, it looks like this : http://cgi.ebay.co.uk/Honda-Accord-Space-Saver-Spare-Wheel-Kit-2008-mod-/150470590040?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2308befe58 . second hand ones do pop up now and again on ebay.