1. Are you certain that your system has the WWAN antennas? It's common that if a system were ordered without WWAN option it would not include WWAN antennas. You would of course have WIFI antennas. 2. If you do indeed have the WWAN antennas, then yes, you could install a WWAN card and attach the antennas. Be careful when disconnecting and connecting the tiny antenna plugs that fit over the tiny posts on the card (kind of like snap fasteners on a coat). They are fragile.  3. You would need to choose a card that is compatible with your desired provider's service. Not all cards are compatible with all providers, so you need a card that they support. For internal WWAN cards, this Dell page has information. Whenever touching components or working inside a computer, wear a grounded wrist strap, also called anti-static wrist strap, ESD wrist strap, or ground bracelet. It's a cheap and sensible precaution. Rest the laptop on an anti-static mat or at least a reasonable alternative such as corrugated cardboard. (Repeatedly touching a metal case part is not sufficient mitigation with modern components.)
Good evening folks, So I am enquiring about installing a WWAN card to install in my E5470, I upgraded the panel to a 1920x1080 as the old 1366x768 panel was broken from my Job, however the laptop has a slot for WWAN and has the antennas for the WWAN card as well as WIFI Antennas. I have been looking at the DW5811e I'm from the UK however I fly from the UK to Southern Ireland & the US, would any of you know if this card would work in these countries, I currently have a Ireland SIM from 02 however when i'm travelling in the UK i just tether my Phone but this won't be an option when in Ireland or US. Something to mention I need internet more than Phone calls as most of my contacts are on matrix-synapse anyway. Regards  
Dell Lattiude E5470 WWAN Card