How to burn rEfit .cdr or .dmg in Ubuntu or Windows?

I don't have Mac OS X installed on my MacBook Pro, but I have Ubuntu and Windows.

I was following this website's instructions to boot faster into Ubuntu without a 30 second delay. However I can't even burn a rEfit CDR image. Do you know how to burn it?

Installing rEFIt - at the sourceforge rEFIt page has a link to the CD Burning Instructions.
^{You may also want to read this TripleBoot via BootCamp page at the onmac Wiki.}

Update on your comments.

• Extensions .dmg and .cdr are used for Disk Images created on Mac
• I suspect the Windows/Linux target file 'rEFIt-0.14.cdr.gz' is a gzipped ISO
  Try the following,
  • gunzip the 'rEFIt-0.14.cdr.gz' to 'rEFIt-0.14.cdr' and,
  • Rename 'rEFIt-0.14.cdr' to 'rEFIt-0.14.iso'

^{If you don't have 'gunzip' handy, use 7-zip.}

Update2:

• The file is just under 7MB so I downloaded it and tried some of the steps.
  The gunzipped file shows these details on my windows machine,

$ file rEFIt-0.14.cdr
rEFIt-0.14.cdr: Apple Partition data block size: 512,  
first type: Apple_partition_map,  
name: Apple, number of blocks: 63,  
second type: Apple_HFS, name: disk image,  
number of blocks: 40896,

• Since its a .gz which opened properly for both of us, chances of it being corrupted are none (unless its corrupted at the source).
• The sourceforege description very clearly says this .cdr should be processed as an ISO. However, this file detail of Apple partition map surprises me a bit. I do not have a Mac handy
  • let me see if I or someone here can figure things out
• One direction to check is: How to burn a mac-disc on windows?

Oh!, There is something very obvious missing here...
These are bug reports from their sourceforge track!

• Your "CD Burn Instructions" are a pile of BS - ID: 2995039, Open
• A CDR file is not an ISO file - ID: 2987447, Closed as Invalid,
  with the following note,

If your CD recording software refuses to burn the image because of the file extension, rename the file. If it refuses to burn the image because of the file contents, file a bug against the CD recording software.
The distributed image file is a perfectly normal sector-by-sector image like any other "ISO" file. It does not contain an ISO9660 file system; instead it contains an Apple Partition Map and a HFS+ file system. That's what is needed to make Mac systems boot from it.

Worked for me on my Ubuntu box: renamed to .iso, then opened K3B, chose 'more options' -> 'burn image' and select the wanted file. First K3B says it's not a valid, but then I chose 'plain data image' on the 'image type' menu on the right and it would just burn it fine! Hope this helps.