It is my understand that it is possible to lend SOAP API Support to Professional Edition users by embedding a 'Partner Token' in the SOAP envolope headers.

I also understand that people have done this to give professional edition clients access to their package that require SOAP API access even though that client has professional edition which doesn't natively support the APIs without an upgrade.

I understand that the same API access rules exist for the REST API (only avalible in ultimate, enterprise, dev. instances) but I'm curious if a similar procedure for 'lending' access to 'professional edition' for the REST API.

Also, anyone whom knows of a good explanation for embedding the 'Partner Token' into the API Calls as described above, as it seems like people have had 'mixed' results...