Do you have access to a running computer and a thumb drive? If so, there are many guides for how to build a bootable USB thumb drive. If not, it may be possible if your phone supports a microSD card an you've got access to a USB-based micro SD card reader. I would guess that if you create a FAT32 partition on the SD card and mark it "active," you could just insert the card into your phone, download the ISO, and extract the ISO onto the micro SD card. Take the card out of the phone and put it in the reader in a USB port on the computer, and it might work.
That said, for the $10 it costs to buy a thumb drive and the 20 minutes it would take to follow any of the "how to install windows 7 from a USB thumb drive" guides, I'd just go that route and save yourself some headache.
--Russel