From the /r/ketogains FAQ
http://www.reddit.com/r/ketogains/wiki/index

The Targeted Ketogenic Diet (TKD) is nothing more than the standard ketogenic diet (SKD) with carbohydrates consumed at specific times around exercise. This means that carbohydrates are consumed on days when exercise is performed. If fat loss is the goal, the number of calories consumed as carbohydrates should be subtracted from total calories, meaning that less dietary fat is consumed on those days. The TKD is a compromise approach between the SKD and the CKD. The TKD will allow individuals on a ketogenic diet to perform high intensity activity (or aerobic exercise for long periods of time) without having to interrupt ketosis for long periods of time.
-"The Ketogenic Diet" by Lyle McDonald

Within certain limits, the TKD can sustain high intensity exercise performance, although perhaps not as well as the CKD. The TKD is generally most appropriate for beginning and intermediate weight-trainers, as it will allow them to sustain exercise intensity without disrupting ketosis for long periods of time. Additionally those individuals who cannot use the CKD for health reasons, but who are also involved in high-intensity exercise, may find the TKD appropriate.

Although experimentation is encouraged, most individuals find that 25-50 grams of carbohydrates taken thirty minutes before a workout enhance performance. The type of carbohydrate consumed pre-workout is not critical and individuals are encouraged to experiment with different types of carbs. Most seem to prefer easily digestible carbohydrates, either liquids or high Glycemic Index (GI) candies as to have them absorb fast in the body and also to avoid problems with stomach upset during training. A wide variety of foods have been used prior to workouts: glucose polymers, Sweet Tarts, bagels, and food bars; all result in improved performance.

Research suggests that carbohydrates consumed before or after exercise should not negatively affect ketosis. However, some individuals find that they drop out of ketosis transiently due to the ingestion of pre-workout carbohydrates. After workout, there will be a short period where insulin is elevated and free fatty acid availability for ketone production is decreased. However, as blood glucose is pushed into the muscles, insulin should drop again allowing ketogenesis to resume within several hours.

Performing some low intensity cardio to lower insulin and increase blood levels of free fatty acids should help to more quickly reestablish ketosis. Post-workout carbohydrates might be expected to have a greater effect on ketosis, in that insulin levels will most likely be higher than are seen with pre-workout carbohydrates. For this reason, individuals may want to experiment with pre-workout carbohydrates first, only adding postworkout carbohydrates if necessary.