You absolutely can do this but it does depend on the nature of your connectivity issue.
If you have no internet access at all there's one set of ways to do it and if you just have slow internet there's a somewhat easier way to do it.
The bad news is that I'm not totally sure about the process and I don't want to mislead you. Kryo would certainly give you the best way to do this but I think he may be off for a couple of days. You can always email
[email protected] for help.
There's also a few folks around that should be experts on this by now, Evil Stormbringer comes to mind, perhaps they'll respond with an answer. If all this fails then you could search through the forums for keywords such as Internet and Install. This topic has been discussed quite a bit in the recent past. I'm sure you could find a post that corresponds to your situation.
If you do respond to this thread it would help to mention which issue you have, no internet or slow internet, because the solution will be different in each case. Sorry I can't give you a better answer.