How can I get nodetool without Cassandra
The easiest (non-invasive) way is probably to download the tarball installation (you'll need to select either a Mac or Linux-based OS for it to allow you to download the tarball).  Based-on your mention of disabling the service, I'm going to guess that you want to accomplish this on Windows.  If that's not the case, please indicate so in the comments.

Un-tar dsc-cassandra-2.0.8-bin.tar.gz to the location you want to run Nodetool out of.  ex:

$ cd /tools
$ tar -zxvf dsc-cassandra-2.0.8-bin.tar.gz


Note: You may have a different application you use for tarballs.  I ran this from a Cygwin terminal.

Find the location of your JRE/JDK (not the bin directory) and set that as your "JAVA_HOME" (System) environment variable.  When you have it set properly, you should be able to query it via CMD:

&gt;echo %JAVA_HOME%
C:\Program Files (x86)\Java\jre7


Once you have JAVA_HOME set, it should work from either CMD or Powershell:

C:\tools\dsc-cassandra-2.0.8\bin&gt;nodetool -h 192.168.1.85 status
Starting NodeTool
Note: Ownership information does not include topology; for complete information, specify a keyspace
Datacenter: datacenter1
========================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address       Load       Tokens  Owns    Host ID                               Rack
UN  192.168.1.85  506.29 MB  256     100.0%  cd39f0fe-ed67-40cf-b6bd-504cedabf497  rack1


This way, you can run nodetool without messing with an installer or services.