multiple instances problem with virtual sites

[CF_fdk]

We are running 4 cf instance on our dev server one per application version. Per
version of the application powers multiple sites, in total 511 sites. Now I
want to add another site bu on installing the connector for this addional site
I get an error
'C:\JRun4\bin>wsconfig -ws IIS -site "dev.site512" -host localhost -ser
ver cfusionappv3 -coldfusion
Error creating the directory C:\JRun4\lib\wsconfig\1-512'
Is there a limit to the number of vertual sites that can be connected on
multiple instances?
I did try to configure Jrun/IIS6 manually by copying the config files of site
511 (c:\jrun4\lib\wsconfig\511) replacing the 'IIS site id' in these config
files and adding the ISAPI extentions in IIS + adding the wildcard mappings.

[CF_fdk]

Anyone? I'm kind of stuck here...