applying for visitor visa from Ireland to Canada.

[MCB]

I am a Brazilian currently living in Ireland under a
student visa. My Irish Student visa will expire in
July/2007 but I am able to extend it if I need to. I
want to return to Brazil in the fall but I really want
to visit Canada on my way home. I have some good
friends in Canadian and I will stay with them and
travel around a little bit. They have offered to help
in any way that is needed to ensure that I can come to
visit.

The problem is that I went to the commission in London
and they said it was tricky because I would be
applying under a student visa from Ireland and not
from Brazil. They said that they would need proof that
I will return the Ireland in order to issue me a TRV.
This is not the case. What are my options if any?

Can I prove my intent to go to Brazil after Canada
with the purchase of a ticket? Will this help?