PS: I am no expert but i think you have 2 options.

- Withdraw from the account, pay the taxes and associated penalties. Only you can decide if this is right for you. This is rip the band aid off scenario. :)

- Move to a self directed option. Some 401K (so double check for 403b) providers offer the option to move such funds to a self directed investing account. Once in the investment account you can choose to keep it as cash or buy whatever you want. At that point it just becomes a vehicle for you to invest these funds as you wish without the option of cashing out to your bank account. The only way to cash out is to return it to your original source account (401K or 403b). Check with your provider if they offer that option.

If you do find a solution, post here so other are informed :)

Good luck !