I am not sure that such work experience is included in the current list of eligible Jobs for Canadian PR.
Please check the CIC website and see what the details are. Here is the link that you can check for the Job categories that are eligible.
http://www.cic.gc.ca/english/immigrate/skilled/complete-applications.asp
Anyways, as a rule, you should be able to prove, that the job was/is PAID. That can be by means of payslips, bank details of salary transfer, official letter from employer etc.
Hope this helps.