From Vancouver:You need to take two ferries - Horseshoe Bay to Langdale drive an hour and a half and take the second ferry to Saltery Bay. From there its a 50-60m drive to Lund, at the end of the road. Leaving on Fridays and returning on Sundays can be a bear, especially on the first ferry - you can make reservations extra $17.50 for the first of the two ferries. The second ferry goes every 2.5 hours or so - check schedules on the BC ferries website. Total fare is approx $130 return for a car and 2 people, goes down to under $100 if you get a BC Ferries Experience card prepaid card for the ferries. It is definitely a trip but very much well worth it.
From Lund:Water Taxi goes from end of the road in Lund, leaving on the hour at busy times from about 8am probably a lot less often when less busy. Reservations by calling ahead, 604.483.9749 are apparently required. Going back it leaves on the half hour - but again how often depends on season and demand. Fares are $10 per adult each way, $5 for children 2-6 and $2 for bikes, and they will take credit cards on the Lund side.
You can leave the car in Lund at Daves parking lot for $6 per night. Or, if you prefer free, up the hill about 1/2km there might be some free parking.