First step... know the law.

Our laws are based on international conventions, treaties and agreements respecting refugees that we have passed into binding domestic law under the Immigration and REFUGEE PROTECTION Act (IRPA) and which are enforced by the courts.

The law permits Convention refugee claimants to enter Canada by whatever means necessary and make a claim for protection that must be adjudicated in accordance with the principles of "fundamental justice" (our version of due process) as set out in s. 7 of the Charter which applies to "everyone" physically in Canada (1985 SCOC Singh case).  And if the claim is successful Canada must offer protection.  

In fact the IRPA at s. 133 exempts refugees from criminal charges and prosecutions in respect of illegal entry and requires that any such proceedings during the claim adjudication process.

The Safe Third Country agreement exploits a technical loophole in the Singh case as persons at POE's are not IN Canada and can be sent back.