SBO and Citrix

Does anyone have experience or knowledge about running SBO through a Citrix client as an ASP solution?

One of our partners is i the process of setting up such an enviroment, but has run into problems when installing the add-ons. It seems that add-ons like the Payment Engine requires the C: drive for installation, and this does not work well with Citrix.

Is this true, or does the add-on installation procedures look for the SBO installation folder without finding it when the environment is Citrix? If the add-ons installation procedures look for the SBO installation folder, how is it done - by looking in the Registry? And through Citrix, does each client have its own Registry?