I am looking to set full trust for a single web part, is this possible? manifest.xml maybe?
Have you tried registering the assembly in the GAC? This is the preferred approach to giving any assembly full trust on your machine:
gacutil.exe \i C:\Path\To\Dll.dll
Hope that helps. Let me know if I misunderstood your question.
You can install a CAB packaged web part to the GAC using
STSADM -o addwppack -filename yourwebpart.cab -globalinstall
If you are using WSP packages you need to set attributes in the manifext.xml file
<Assembly Location="yourassembly.dll" DeploymentTarget="GlobalAssemblyCache">
and call
STSADM -o AddSolution -filename yourwebpart.wsp
STSADM -o DeploySolution -name yourwebpart.wsp -allcontenturls -immediate -force -allowGacDeployment
Of course you shouldn't really install to the GAC if you can help it, setting CAS is the preferred way.
As far as I recall manifest.xml is correct, and you specify the CodeAccessSecurity.
This article has a detailed description about it http://www.dotnetmafia.com/blogs/dotnettipoftheday/archive/2007/07/05/how-to-configure-code-access-security-for-a-web-part.aspx
when you deploy your solution then you deploy it with the -allowCasPolicies flag on
I'm not sure i'd want to put a webpart into the GAC