There wasn’t an official API for this but I’ve just added support for q.SqlFilter or q.WithSqlFilter() in this commit which will let you customize the Sql with:
var q = db.From<Person>()
.Where(x => x.Age == 27)
.WithSqlFilter(sql => sql + "\noption (recompile)");
var rockstars = db.Select(q);
Before this release you could modify the q.HavingExpression to achieve a similar result which will append the custom SQL expression to the end of the SQL Statement (i.e. in-place for where the HAVING sql expression would be), e.g:
var q = db.From<Person>()
.Where(x => x.Age == 27);
q.HavingExpression = "option (recompile)";
var rockstars = db.Select(q);