Hi
1. Unless you are an International Student at a Canadian school the employer would have to either get an approved LMIA or you would have to apply under the International Experience Canada (IEC) if you are eligible and meet the following criteria.
The type of work permit you get in the International Co-op (Internship) category is an
employer-specific work permit.
This category is for you if:
http://www.cic.gc.ca/english/work/iec/eligibility.asp
- You’re a student registered at a post-secondary institution
- You have a job offer for a work placement or internship in Canada
- You need to do this work placement or internship to complete your studies
- You’ll work for the same employer in the same location during your stay in Canada
2. You can't just roll up to a port of entry and request it.