Unfortunately, you can't not if you're planning to edit that video in Premiere Elements. (We do NOT recommend using a FireWire/USB converter or using a cheap digitizer like the Dazzle unit to capture your video.)
The best solution is to capture your video to a computer that does have a FireWire connection and then move the video somehow to your main computer for editing.
As more and more laptops are doing away with FW-400 (IEEE-1394a, iLkinK) and PCMCIA, or ExpressCard slots, the only good workaround is to press an older computer into service, WITH and IEEE-1304a connection, or free slot to add an IEEE-1394a card, which is cheap. Then, using an external HDD, or a networked connection, transfer the Captured files to the laptop for editing.
The lack of an ExpressCard slot is what is holding me up for a new laptop. Clevo (major laptop MoBo mfgr.) discontinued adding one, but they are supposed to come back in May, 2012. I am anxiously waiting.