Printing a Scroll

What version of Microstation & what type of plot driver are you using, .plt, .pltcfg? Are you printing to pdf or direct to printer?

Microstation V8i select series 10 using a .pltcfg to print drawing  to a PDF. 

So you took the Bentley supplied pdf.pltcfg file and modified that for what you need? For your printing preferences ensure that Allow Paper Size Editing is enabled. This will allow you to change the paper size right in the plot dialog on the fly. So even though you may pick a paper size that is set as 22x34 you can change that to whatever you want.

you also need to consider scaling , what I do is draw a rectangle the largest std size width for me  in metric its AO which is 841mm x1189 mm

now we draw in metres  so if I draw the sheet boundary as 841x1189 m its already 1:1000 for plot down to paper size A0..

now I place this over my map and determine if it need scaling up or down and  also stretching length so lets assume  it was  wide enough  but  needed to be 2000 m long , now I know to create a custom sheet  841x2000m and it will be  1:1000...when plotted to paper... you can work out different scales your self this way...

I also edit the printer to have these handy rollplot  paper size  for future roll plots, A0x1500, A0x2000, A0x2500, A0x3000

That's how we did it at my old workplace. We just defined a few paper sizes for several different scroll plot lengths, and (I believe) there was a setting on the printer to conserve paper by not using any more paper than the plot actually needed.