Mastercoin (as well as other alternative coin) are available on the blockchain:
https://masterchain.info/Address.html?addr=1JwSSubhmg6iPtRjtyqhUYYH7bZg3Lfy1T¤cy=MSC

They hide under http://xkcd.com/936/
Let's see you collecting this 0.1 MSC, as well as the 5 SBP.

It is trivial to add this address to your wallet:
1. visit https://masterchain.info/wallet.html
2. create password
3. add address - private key is 5KJvsngHeMpm884wtkJNzQGaCErckhHJBGFsvd3VyK5qMZXj3hS

Now you see your balance.
Clicking on the balance converts to the theoretical USD value (~28 USD).

To spend mastercoin protocol based coins, you need some funds, but if you put some funds on this address - they will be gone immediately
The solution probably involves a set of transactions sent together with wise fee calculation.

Let's see who takes those coins
Good luck!