Kamloops is a city in Canada.
The best place to hitchhike west through Kamloops is to wait at the off-ramp by the Flying J truck stop a ways before town.
If you are dropped off in Kamloops, it's likely best to take the city bus #17 to the BC Wildlife Park on the outskirts of town, and from there walk out onto the highway past the Lafarge plant, which doesn't have a prohibition on hitchhiking at that point.
Places to avoid
Kamloops has a bit of a reputation as a drug city, but then again you are in British Columbia so you should be fine. Just keep to your wits when finding a spot to sleep.
Other useful info
Kamloops in general is a mess of highway on both sides of the city, so if you are in the position to plan where you are dropped off, go for somewhere before or after the city limits. If you are dropped off in the city, take one of the city buses to the outskirts if you can.