Create a single new file that is smaller, but in proportion, and place the original page in that, then print scaled and enabling tiling and overlap.
Create multi-page spreads that equal the total width (and you can even use different page sizes here to control the breaks) and add a bleed allowance all around, place the original across the spread (you will need enough spreads to equal the height, and you cannot view them all at once), then print the individual pages with bleed.
Hello gareth, not sure if the info' below will be of use, but I will give it a go.
(I am using Indesign CS5.5)
1. Create your desired page size.
2. Then create 2 or 3 more pages
3. Open the pages window (from top menu - window - pages)
4. (fig 1) From the pages menu click top right down arrow to get the menu and uncheck ‘Allow Document Pages to Shuffle’.
5. (fig 2) From the pages menu, drag page 2 and 3 next to page 1, see fig 3 for result.
6. (fig 4) Place text/image across the pages you have created then save as a Pdf.
I do it similar, but I use facing pages. This has the advantage, that the pages are sticking together (as for a book cover), and if one page hase to be resizied (for a book spine important) the other pages will move accordingly.
You need to uncheck in this case "Allow selected Spread to Shuffle" which will include the page numbers of the extended spread in brackets.
If you are using OSX I have an AppleScript that might work.