You can get multi-adapters for cigarette lighter plug socket style. I have bought mine from K-Mart and DSE I think. They're very useful!
The thing you have to watch out for is treating your "jumpstarter" nicely with respect to battery usage. SLA batteries don't like to be drained to empty or near, and if you bought one of the cheap jumpstarter type products there's a good chance it's got a cheap SLA in it so will be more susceptible to being overloaded with too much power drain.
Roger.