In order to just insert alphas and betas , I write a's and b's, select them and set Symbol font for them.
Obviously, to have this operative, the admin must set it first , in Configuration ->Editor settings -> add Symbol font. I don't know if there is a limit on how many fonts can be added. The admin adds one at a time, and always appears a new blank entry box.this way, it is not inserted α but <span style="font-family: symbol;">a
First is shorter, but both yield the same result.