This is a guide that i got from pocketgamer.co.uk all credits goes to them.
DISCLAIMER: I DO NOT OWN THIS GUIDE SO ALL CREDIT GOES TO pocketgamer.co.uk
enjoy
Step 1:
Before doing anything else, you need to check if your PC or laptop's wireless network card is compatible with the software. If it is, it'll be included in this list. If your card isn't included it won't work. You'll have to borrow or buy a compatible one.
Step 2:
Make sure you have your original card drivers and instructions handy. This is vital for changing your network card back into one that you can use for accessing your home network and connecting to the internet. When you're absolutely sure you've done this, download the DS driver here. Unzip it by right clicking the file, selecting Extract all.
Step 3:
Open Control Panel by clicking Start, then Settings, then Control Panel. Double click System and choose the Hardware tab. Click Device Manager. Click the plus icon next to network adapters then find your network card on the list. Right click it and select Update Driver... to start the Hardware Update Wizard.
Step 4:
Choose 'No, not this time' if you're asked if you want to connect to Windows Update, then 'Install from a list or specific location' on the next screen. Tick 'Include this location in the search' then click Browse and choose the directory you extracted the DS driver to earlier and click 'winxp' then 'i386' then Ok. Click Next one more time, then Finish.
Step 5:
Download the wireless multi-boot application and unzip it. Download the demo of your choice from this page, saving it as 'demo.nds' in the folder you just extracted the Wireless Multiboot Application to. Open that folder then click and hold the left mouse button on your newly downloaded 'demo.nds' and drag it into the 'data' folder. Right click wmb.exe and click Create Shortcut. Right click the shortcut you just made, select Properties and add ' -data demo.nds' to the end of the 'Target:' box, after the closing quotation marks. Click Ok and run the shortcut by double-clicking it.
Step 6:
What a lot of work. Here's the fun bit: start your DS and select DS Download Play. If you've done everything right the name of your demo will appear. Click it to begin the transfer then start playing. Remember to reinstall your network card's original drivers when you've finished playing the demo.