Buy a cheap
wireless (less camera shake) remote. Here's the one that I used for over a year till it got burned...
Amazon.com : PIXEL RW-221/E3 Wireless Shutter Remote Control Release for Pentax K-5/K-7/K10/K20/K100/K200
The trick is to set the
camera to
continuous shooting, and the
remote to
Bulb mode. Then when you hit the button on the remote, it thinks it's doing Bulb, and keeps the shutter continuously depressed. The camera is set to continuous, so it keeps shooting as long as the remote tells it to. When you're done, hit the button on the remote, and it stops! Of course, if you need longer than 30 sec. exposures, that won't work, you'll just have to use Bulb like it's made to be used.
This may not be what you're looking for, since it doesn't have a timer, but it's still a nice option to have, and wireless is very handy! Be aware that if you take the remote out of range, it will stop your sequence!