Drove an hour from work to attend a company approved seminar. Since I'm hourly, can I count that drive time as work time?

Were you already at work and on the clock, if so then yes.

Yes, if you were already at work, left work, then you are still on the clock.

Travel time is considered time worked if you are under the control of the employer. So since you drove from work straight to the seminar, that is considered compensable.