Guys:
There are several ways to get in and avoid detection. All depends on your your skill level with a compass and/or GPS, or you willingness to get a little sweaty and dirty. Basically...your commitment!
First off, if you can get a friend to drop you off somewhere near the grove, and then wait for your cell call to pick you up, the problem of parking no longer applies and many more entrance routes open up to you.
There are several good maps on this sight that show the layout, and for that matter, you can even use google earth to get a visual as well as Longitude/latitude numbers (for GPS). If you know how to use a compass, you can easily find numerous start off points around and near the grove to take a reading and bushwack in. Much easier on moonlit nights obviously.
Also, there is a creek that runs north/south along the western edge of grove. You can walk the bike trail that runs along the north side of Midlothian turnpike and duck in under the bridge that spans the creek. Wear dark or camo clothing. Stay to the woodside edge of the trail and keep an eye out for obvious police cars. If you see one, step into the woods, crouch, and you disappear. Have done it many times. This creek is also great when the water table is low in the summer. You can sometimes even walk down it. Either way, it's a great marker.
Another, easier, surer way to do it, is go to the grove during the day, and bushwack backwards towards a landmark/entrance point of your choosing. There are many deer trails that lead out to the street at various locations, as well as back to the soccer field south of the grove. Get to know the route and use it at night.
The tower (and the light on it) make a great reference point at night. When in the woods, look up. You can also use the sounds of the cars on the turnpike to keep yourself orientated properly. The biggest "no-no's" are using a flashlight or making alot of noise. However, the biggest mistake people make with a flashlight is shining it up, or at eye level. So, if you must use one, get one with a red or yellow cap and crouch low and shine it down at the ground to find the trail. Holding the light perpendicular to the ground, about 10" high when in the cover of the trees will let you see the trail as well as any obstacles. Lights up in the trees can be seen from far away.
The other thing good about knowing these trails is that you have more than one "escape" route should the county's finest decide to come calling. (again, see note about getting dropped off. Being able to choose your exit point and time are a great advantage to escape) I am not being too specific here exactly for that reason.
(I find it funny that on a public board, some of you guys are telling the FPPD exactly where you park, what trail you're going to enter on, what day your going--next full moon-- etc. Might want to rethink that.)
All of these take a little work and effort, but trust me. Being in the grove at night, in silence, undected, without outside interference or interdiction is well worth it.
Good luck