It actually says right here:
http://www.immigration.gov.sk.ca/skilled/?Anc=7e8f4b1d-79b4-4120-8b3a-599d97fc7875&Pa=ebd9edd0-fecd-4503-b6f7-70a7366de4c4Eligibility
You may qualify to apply under the SINP Skilled Workers Category if:
* You live outside of Canada or you have proof of legal status in Canada, you are not a refugee claimant and you have one of the following:
o An offer of permanent, full-time employment in Saskatchewan either in an occupation or trade in the National Occupational Classification (NOC) Matrix level "A" or "B", or in a designated trade in Saskatchewan (Skilled Workers/Professionals Sub-Category);
o An offer of permanent, full-time employment in Saskatchewan in a management position in the NOC Matrix level "0" (Critical Occupations Sub-Category); or
o Have worked in Saskatchewan for at least six months on a temporary work permit either in an occupation or trade that is in the NOC Matrix level "A" or "B", or in a designated trade in Saskatchewan (Existing Work Permit Sub-Category).
Your employer would have to write up an official job offer. SINP can tell you what it has to say in there. He might need to apply for an AEO (arranged employment offer) from Service Canada. It is supposed to be easier to get than an LMO.