I have 6 switches that control the same light. I believe currently it's set up with two 4-way switches and four 3-way switches. Can I use this system?

Yes, the MACL-153M can be used in 4-way applications if you are using one MACL-153M with companion dimmers (model: MA-R) in the remaining locations. Please see the following specification sheet for more information: (http://www.lutron.com/TechnicalDocumentLibrary/369613a.pdf).

If they're controlling the same light, you should have two 3-way switches and four 4-way switches. Typically, one 3-way is tied to the incoming power on the black (common) terminal and there are two "travelers" connected to the other two terminals of the first 3-way. There will be two "travelers" between each of the 4-ways and then to the last 3-way. The last 3-way will need its black common terminal tied to the light fixture it's controlling. -- These dimmers can have one "master" and up to nine companion "slaves", so you should be able to do what you'd like to do. However, there are a couple of things you should consider. First, in this discussion, I haven't included the white (neutral), nor the green or bare (ground) wire. Both will need to run from the source of power to the light and each device needs to be properly grounded. The slaves don't need the neutral wire, but you should run a white neutral to each box anyway. Many even newer devices (with "smart" functions) will need that neutral and you should put it in now, if it doesn't already exist. It's got to run to the end fixture anyway, so it's not really an added expense. Second, if your Lowe's store is like ours, they don't stock the companion dimmers in the store, except for those packaged with a master. They will order them for you, or you can probably order them online yourself. The instruction sheet that comes with each device is pretty good and includes diagrams. Be sure to mark the travelers as you take out the old switches, so you can get them back on the correct terminals. Read the instructions before you begin and then follow them as you proceed. If all else fails, they have a help line. I've never had to use it, but suspect it's pretty good based on the effort they put into the instructions.