With a table top smoker, trout should just be patted dry with paper and seasoned well with salt, pepper and maybe some herbs, then smoked for about fifteen minutes (depends on the thickness of the filets: just open up the smoker and try the fish with a fork after 10 to see if it flakes). Wait until the smoke is going well before you put the fish in.
Cod roes are usually cold smoked, and I'm still building mine so I can't share any experience, but theres no reason why you couldn't try it. My guess would be to slice the roe thick (about 5-6cm) and remove the membrane, then season lightly and smoke for only 10-15 minutes. If it's too smoky then a covering of oil will reduce smoke penetration.
You might also want to blanche the whole roe first, then cool, slice and flavour it up in the smoke.
Just a few thought.