As for the ticks, I'm not even sure you can dry-clean a pack, so that won't work. You can dunk it in a tub full of hot water and try to drown the bastards, but ticks are pretty resilient and the jury is out over whether you can actually kill them this way. They have a habit of escaping.
So where does that leave you? To be honest, I'd go chemical. My suggestion would be a pet shampoo that kills ticks and fleas and that contains pyrethrin. Let the pack soak in a solution of tick-killing shampoo and warm water for 10 to 15 minutes, rinse thoroughly, and dry. That should account for your tick problems. And pyrethrin doesn't leave any residue and isn't hazardous to humans so long as you're not swallowing gallons of the stuff.
I'm not sure what you could do by way of prevention. Hang a flea and tick collar on your pack, I suppose, but that's not something you'd necessarily want to be exposed to yourself. I think the best solution is to treat the pack after you return home to ensure any hangers-on don't have a chance to latch onto something tastysuch as you.
Get more backpack know-how in Outside's 2004 Buyer's Guide.
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