Yes it can be done, but you have to realise you will have no life for the next couple of years or so.
You need to prioritise and also need to have a reasonable employer. It also helps if you live near an airfield.
The best thing is to have a word with your employer to see what can be done there. Flexible working hours, working overtime in return for time off (when it suits you), and unpaid leave in quieter times are things which could suit both you and your employer.
I worked 3 jobs and spent about 3 years doing my CPL/IR.
I spent almost every evening, weekend, holiday even lunch hours sometimes, studying or flying.
You have to make it your priority. It won't be easy, but if you can block everything else out you can do it. You need real discipline and will power though.
But just think of all the time off you'll get when you get that big airline job!
You could also combine a semi-holiday with flying, for example, do some of your flying in the USA.
Its more than worth it in the end. And I also think its a strong point in your CV/letter and interview. Employers like to see that you worked so hard, with such dedication, as it shows you can stick with something and also that you are a fair bet to get through any kind of flying/ type rating course.
Just come post on here when you are losing your enthusiasm and we'll sort you out!!