Using BDE to Restructure a table

Can anyone point me to a good piece of code for accessing the BDE for the following purposes:

1.  Adding new fields to a table
2.  Adding indexes
3.  Modifying field sizes
4.  Adding security

I can perform 1 and 2 with SQL, but I haven't found a way to do 3 & 4.  

Any help would be appreciated.