OK, before this I considered this song to be Bono just saying nonsense! But now I think I got something.
As Aaron said, the whole thing is about a person who is escaping from a war-hit city...he's trying to find a new home.
And you know it's time to go
Through the sleet and driving snow
Across the fields of mourning
Light in the distance
"fields of mourning" refer to the city's people, now mourning the people they lost in the war. He knows it's time to go, he has to move on and find a new home. The "driving snow" could be a metaphor, or just something to make the scene more dramatic...it does the job!

And you hunger for the time
Time to heal, desire time
And your earth moves beneath
Your own dream landscape
He wants some time...he wants some time to stop, heal himself from the wounds (physical/psychological) of war, a time to go after his desire and forget about his problems (but he can't, he has to move on). So he starts to dream.
He keeps walking...and also dreaming of a better place to be, he's trying to forget the scenes of war, so, his earth is moving beneath him (he is walking forward) but the landscape in front of his eyes are his dream landscape, he tries not to see what the war has done.
Oh, oh, oh
On borderland we run
I take this to be part of his dream...he is dreaming to run freely on borderland...that is, no war (he couldn't run around so easily round the border if there was war

Or maybe it's not a dream, he's running to another country...crossing the border, so he's running on borderland.
I'll be there
I'll be there
Tonight
A high road
A high road out from here
He's giving himself hope..."I'll be there", "I can make it", just find a road that takes you out of this war-torn place!
The city walls are all come down
The dust, a smoke screen all around
See faces ploughed like fields that once
Gave no resistance
Describing the war-hit city and it's people. The walls have come down, lots of dust, the people are so sad and angry, their faces look like a ploughed (or is it plowed?!) field. You do get the resemblance, right? An angry face looks like plowed field, something like this:
See?! Lots of holes and stuff in there

Anyways...these were all kind and happy people before (they "gave no resistance"), but now they are angry.
And we live by the side of the road
On the side of a hill
As the valley explode
Dislocated, suffocated
The land grows weary of its own
A clear description of the man's journey...he lives by the road, and cities around him are getting bombed, valleys around him explode. He's dislocated, feels helpless, suffocated...everything seems wrong, even the land is tired of itself!
Oh come away, oh come away, oh come
Oh come away, you say
Oh come away, oh come away, oh come
Oh come away, you say
Hard to explain really...maybe it's the voice of hope in his head, telling him to not give up, keeps telling him to "come away", move on from those exploding valleys, forget the problems and move on!
Oh, oh, oh
On borderland we run
And still we run
We run and don't look back
I'll be there
I'll be there
Tonight
Tonight
Seems the borderland not being considered a dream works better with this. He's running around the border trying to escape, after the voice telling him to "come away", he's found hope again, he runs, doesn't look back and keeps telling himself :"I'll be there!".
The dreaming theory could go like this: he dreams of running on the borderland free, and tells himself :"I'll be there", meaning :"that dream will come true", he's giving himself hope.
I'll be there tonight... I believe
I'll be there... somehow
I'll, I'll be there... tonight
Tonight
Hope-giving again...Bono sings this bit beautifully, making it sound desperate yet hopeful.
The wind will crack in winter time
This bomb-blast lightning waltz
No spoken words, just a scream
First line seems dramatic stuff again, the rest is a description of how he feels about all that he's seeing. "No spoken words, just a scream". Imagine having lost everyone you know in a matter of minutes, and now walking alone in the desert trying to find a new home...that's how you'll feel!
Tonight we'll build a bridge
Across the sea and land
See the sky, the burning rain
She will die and live again
Tonight
OK...this...I can't explain this one so well! Seems like after each verse of hopelessness, there is one of hope giving. The last verse (the scream) sounded hopeless, now this one's giving hope, "we'll build a bridge", we'll move on, we'll make it through. "She will die and live again", I think she is his country, his city, his home. It will die in the war, but he's hopeful, he's sure it will live again.
Or it could be as Aaron said, not his companion, but someone he loved and lost in the war. She will live forever in his heart.
And your heart beats so slow
Through the rain and fallen snow
Across the fields of mourning
Lights in the distance
He's losing hope again (the system works! One verse hopeful, the next hopeless!

Oh don't sorrow, no don't weep
For tonight, at last
I am coming home
I am coming home
Telling himself: no need for more sorrow, no need to weep...at last, I found a home...I am coming home!
BUT, as it is not his real home (he's going to a new home to start again), it's not an actual homecoming, it's A SORT OF homecoming!
