Hi,
Sure!
Given this enumeration as an example:

You can insert a line here with the following code:
// insert into enumeration
var sqlFields = "INSERT INTO campaign_dev_DB.neolane.XtkEnumValue (iValueId, iEnumId, sLabel, sName)";
var sqlValues = " VALUES(GetNewId(), 15131, 'Inserted from Javascript', 'insertedFromJS'))";
sqlExec(sqlFields + sqlValues);
The end result will be:

Note: Take into consideration that you need to find a new ID for each line if you want to insert. Depends on the client setup.
You might need to query xtkNewId to get a new ID (and then increase it!):
select IdSeed XtkNewId where sSequence = 'xtknewid';
Other operations such as edit values, remove values, can also be done via SQL in JavaScript.