Look no farther than my thread in this very forum here
Here is how you can create your bootable pendrive.
1. Download the latest version of MultibootISOs from here
2. FAT32 format your pendrive.
3. Run Multiboot ISOs and select your pendrive.
4. From the list select "Try an unlisted ISO", browse to the ISO and click "Create"
And that is it. Check the menu.lst to confirm that your ISO is listed. If not edit the menu using Notepad to include it.
(In the previous versions, there was no provision to try an unlisted ISO. One had to select atleast one ISO from the list, allow the program download it and then create a bootable pendrive in the first instance. Thereafter one can copy any bootable ISOs to the pendrive and then edit the menu.lst to include it. With each new version, the author has incorporated improvements. I have not tried the new version, but you should have no difficulty after going through my thread.)