If you want to run a python script, you will need to run it through a batch file using command line adapter. Other than that, I don't think there is any way to run individual python script in RQM.
As RQM does not provide Squish adapter, it may be hard to find any good doc. But I do see someone did that from:
http://doc.froglogic.com/squish/4.1/qt/ao-rqmintegration.html
Looks like it is from froglogic(http://www.froglogic.com/), you may have seen this though.

Yes, its possible to execute individual python scripts from within RQM. A quick and dirty way to run a python file is to configure RQM via the following steps:
(1)Create a RQM command line test script with the following values:
--Command Line Script Details -->Use test resources that are local to a test machine = true
--Command Line Script Details -->Command = C:\Python33\python.exe
--Command Line Script Details -->Arguments =C:\testscripts\pythonWrapper.py
Note, the "C:\Python33\python.exe" & "C:\testscripts\pythonWrapper.py" files need to be located on the remote automation machine where the command-line adapter is installed.

With that being said, I recently needed to run RQM command line test scripts using a python test automation framework, and I needed to make the RQM test scripts Operating System agnostic. Here are the steps I took to complete this task:
(1)Installed Python in the following directly on the remote automation machine, C:\Python33
(2)Updated the start.bat file with the following -D argument, -Djava.io.tmpdir=C:\Python33. Note, the same would need to be done in the start.sh with the exception of the filesystem path being different, eg -Djava.io.tmpdir=/opt/Python33
For example, here is how the command in the file was originally configured:
java.exe -Dlog4j.configuration=file:.\log4j.properties -classpath "%filecontent%" com.ibm.rqm.adapter.commandline.QMCommandLineAdapter %*
And here is how the command was configured after my update:
java.exe -Djava.io.tmpdir=C:\Python33 -Dlog4j.configuration=file:.\log4j.properties -classpath "%filecontent%" com.ibm.rqm.adapter.commandline.QMCommandLineAdapter %*
(3)Put the python file I want RQM to run in the following directory, C:\Python33\Lib.
(4)Create an RQM Command Line test script (eg "Python Wrapper") with the following configurations:
--Command Line Script Details -->Use test resources that are local to a test machine = true
--Command Line Script Details -->Command = python
--Command Line Script Details -->Arguments = -m pythonWrapper
--Execution Variables -->Include built-in variables = true
Note, the pythonWrapper.py file is the phython file which will be used by all RQM test cases to run tests via my python test automation framework.
(5)Created several test case, with different execution variables, and associated each of the test cases to the "Python Wrapper" RQM test script.