Guess it depends upon what style lager you are brewing. For a German style, I wouldn't add anything-let the malt do its job. The orange peel you mention is usually for Belgian style ales, along with about 1/2-1 tsp of coriander, or maybe 1/2 tsp grains of paradise, both crushed. I know that the True Brew lager kits contain ale yeast (according to my LHBS), but not sure of the rest. If they do, go ahead and add other spices, etc. Use your imagination, but I would suggest not going overboard-very hard to correct an over-spiced beer, unless you dilute it.