Pierce the gooseberries several times with a toothpick. Finely zest the lime and squeeze the juice. Heat the lime juice and 4 tablespoons of peach liqueur. Pour over the gooseberries and let soak. Beat the egg yolks, sugar and lime zest until fluffy. Gradually stir in the mascarpone. Mix the remaining peach liqueur and rum. Drizzle the ladyfingers with the rum mixture. Alternately layer the ladyfingers and mascarpone cream in a baking dish. Press the gooseberries into the cream. Serve dusted with cocoa powder and garnished with mint.