I'll sketch out notionally what the process could be, although the steps I will describe in sequence will be intuitive. They're not necessarily under the legislation chronologically.
Notionally the first step would be for a developing country, an eligible importing country, to notify the WTO, if it's a WTO member--or Canada, if it's a non-member--of its need for a particular drug. It would identify the drug and the quantity needed.
Then it depends on their development status. If they're a least developed country, they don't have to indicate anything. If they're a developing country, they have to indicate that they have insufficient manufacturing capacity for that drug. If they're another category of developing country, which has agreed to avail itself of the regime only in situations of extreme urgency or national emergency, they would have to indicate that.
That would be notional step one.