Question #1: Can it be done?

Answer: Not before age 55 (in the vast majority of circumstances). Even when you do reach 55, you need to check your 401(k)'s Summary Plan Document (SPD) to see if this type of "In-service Distribution" is actually allowed.

If you find the documents relating to your 401(k) to be too confusing, get with a Financial Advisor that specializes in Retirement Plans (usually someone with the CRPS or ERPA designations).

Question #2: Should it be done?

Answer: I applaud your desire to diversify your Retirement Fund, but would suggest you look more into simply investing more of your money into your overall Retirement Fund. Look at funding your IRAs separately from the money in your 401(k) (usually having a bit in both the Traditional Deductible and the Roth IRAs is a smart move).

Before engaging in Retirement Planning on your own, though, I still have to caution that your debts should be low and your Emergency Savings well-stocked in case of a lay-off. For any questions on what best practices to use for your situation, look around the neighborhood for a Financial Advisor (with an understandable preference toward Fee-Only).

Any more questions, or just need clarification on any point, just respond to this thread and those of us in the know will help as we can!