glmnGrid <- expand.grid(alpha = c(0,  .1,  .2, .4, .6, .8, 1),
                    lambda = seq(.01, .2, length = 40))

ctrl <- trainControl(method = "cv",
                 number = 10,
                 summaryFunction = twoClassSummary,
                 classProbs = TRUE,
                 index = list(TrainSet = pre2008),
                 savePredictions = TRUE)

glmnFit <- train(x = training[,fullSet],
             y = training$Class,
             method = "glmnet",
             tuneGrid = glmnGrid,
             preProc = c("center", "scale"),
             metric = "ROC",
             trControl = ctrl)

glmnetCM <- confusionMatrix(glmnFit, norm = "none")

Reference
Prediction     successful unsuccessful
  successful          507          208
  unsuccessful         63          779

> dim(training)
[1] 8190 1785
> length(pre2008)
[1] 6633
> 8190-6633
[1] 1557

ctrl <- trainControl(method = "LGOCV",
                     summaryFunction = twoClassSummary,
                     classProbs = TRUE,
                     index = list(TrainSet = pre2008))