This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
I think you can still use the original range for the slider, but Michael is right about the tick spacing. Use larger intervals, like 10000 for minor and 100000 for major. Also, you'll probably have to change the preferred size.
I tried the following and after resizing a bit manually, it worked just fine: