This's for people who can't pay for TOPANGA League ticket using credit card.
First of all, you need a Niconico account. Sign up if you don't have one. It's free.
1. Obtain WebMoney code. Either buy it online or ask your friend in Japan to buy from average convenient stores. You don't actually need the card, you need only the 16-character code. You can buy the code from Play-Asia using PayPal. The site is safe, but it's up to $20 more expensive than the actual value. Buy 5,000 points (5,000 yen) of WebMoney there, and then you should receive the code instantly.
2. Find the link that sells TOPANGA League ticket (such as this). Or look for big "Purchase Net Ticket" button which is on the stream pages, then choose the ticket you want to buy.
3. Next, you'll be informed that you don't have enough Niconico Point to pay. So you need to click "Purchase Point" button.
4. Let's say you want the season ticket that costs 3,500 points. Choose to buy 3,000 points first.
5. Choose WebMoney as payment method. (Click the logo.)
6. Confirm the amount.
7. Enter the 16-character WebMoney code and click the button to complete the payment.
8. Buy 500 points using the same method. (Enter the same 16-character code again.)
9. Now you have 3,500 Niconico points and ready to pay. Click "Purchase Net Ticket." There'll be two confirmation messages to click.
10. Done. You can now watch it live. If you want to watch the recorded stream, click yellow Timeshift button (there's one every stream page), then click red option. (A recorded stream will be ready 30 minutes after the live show.)
Warning: After spending 3,500 yen, your WebMoney code still has 1,500 yen left. Keep the code. You can use it in the future purchase. (You can check balance here.)