As far as Supplementary Welfare Allowance is concerned, if you work 30 hrs or more per week, you don't qualify for anything, regardless of what you earn.
If you work less than 30 hrs per week and earn less than the equivalent SWA rate for you (see below), you may have an entitlement. You will be asked to claim any SW entitlements you are eligible for (e.g. sign for Jobseeker's for the days you're not working). If you're under 25 and living at home with working parent(s), you will be means-tested on their income as well.
The SWA rate is €196 for persons 25 and over, €150 for persons aged 22-24 and €100 for persons aged under 21.