Not automatic, at least not in this version. I will see if I can change that for the next version. I don't expect a new version in 2013 anymore though.
Best way is to use regex in Sigil or another editor I guess.
*Update*
The change is made, in the next version (again, I don't expect to release it in 2013) you can choose between:
- 1, 2, 3, ...
- a, b, c, ...
- A, B, C, ...
- i, ii, iii, ...
- I, II, III, ...
- *, †, ‡, ...
It will be a setting.