from the Marriott rewards T&C for earning miles:

Charges which do not qualify for miles include taxes applied to the room rate, paid outs, purchase of Marriott gift certificates, charges for Marriott contracting services, and catering or banquet functions charged to the guest room account.

From this I would think no, but in the same document it later says that you can earn miles if you are an event or banquet planner, so I'm not sure. To be safe you should probably call the elite line and ask a supervisor, or the manager of the hotel where you are planning this because I believe it is up to their discretion as well. If not miles, you could probably get MR points out of it, which with your silver bonus would still do pretty good.

Here is the T&C for earning miles:
http://marriott.com/rewards/terms/miles.mi