How do I install this script into PhoneGap for iOS

I have come across the need to do this myself. I am an IOS developer, but needed to use phonegap to keep costs down for multiplatform dev.

Anyway, i fixed your code. As, i guess, you dont want to spend your time learning obj-c, you just need to replace the contents of your MainViewController.m with the following:

#import "MainViewController.h"

@implementation MainViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
    }
    return self;
}

- (void)didReceiveMemoryWarning
{
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
}

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    return [super shouldAutorotateToInterfaceOrientation:interfaceOrientation];
}

- (void) removeBar {
    // Locate non-UIWindow.
    UIWindow *keyboardWindow = nil;
    for (UIWindow *testWindow in [[UIApplication sharedApplication] windows]) {
        if (![[testWindow class] isEqual:[UIWindow class]]) {
            keyboardWindow = testWindow;
            break;
        }
    }

    // Locate UIWebFormView.
    for (UIView *possibleFormView in [keyboardWindow subviews]) {       
        // iOS 5 sticks the UIWebFormView inside a UIPeripheralHostView.
        if ([[possibleFormView description] rangeOfString:@"UIPeripheralHostView"].location != NSNotFound) {
            for (UIView *subviewWhichIsPossibleFormView in [possibleFormView subviews]) {
                if ([[subviewWhichIsPossibleFormView description] rangeOfString:@"UIWebFormAccessory"].location != NSNotFound) {
                    [subviewWhichIsPossibleFormView removeFromSuperview];
                }
            }
        }
    }
}

- (void)keyboardWillShow:(NSNotification*) notification {
    // remove the bar in the next runloop (not actually created at this point)
    [self performSelector:@selector(removeBar) withObject:nil afterDelay:0];
}

@end

As a word of warning, this is a bit of a hacky solution (but then so is using phonegap!), and may break in future versions of iOS. But i guess we fix that when it comes to it…