Please Start -> All Programs -> Administrative Tools -> SharePoint Central Administration -> Virtual Server Configuration -> Configure virtual server settings, select the virtual server you want to configure, then click Define managed paths, at last please add an Excluded path named inlinefiles.
Then please create a folder named inlinefiles in C:\Inetpub\wwwroot, and grant the full control perms to everyone or the users using InfoJet EditPart.
Then please add the key <add key="InfoJetSoft.Service.InlineFilePath" value="/inlinefiles" /> to SharePoint's web.config.
In WSS 3.0, no need to config the excluded path in SharePoint Central Administration, please create the folder inlinefiles in the root folder of the virtual server directly.

Please add the key such as <add key="InfoJetSoft.Service.TempFolder" value="c:\log" /> to SharePoint's web.config. Then please grant the full control of "c:\log" to everyone. By default, InfoJet Service needs to extract the files in form templates(xsn) to the system temp directory. But in some condition(such as impersonation is enabled in SharePoint), InfoJet Service has no perms to access the folder or files in it, so please add this key.

Please add the key such as <add key="InfoJetSoft.Service.TempFolder" value="c:\log" /> to SharePoint's web.config. Then please grant the full control of "c:\log" to everyone. By default, InfoJet Service needs to extract the files in form templates(xsn) to the system temp directory. But in some condition(such as identity impersonate is enabled in SharePoint), InfoJet Service has no perms to access the folder or files in it, so please add this key.

InfoJet EditPart needs cache the credentials in SharePoint's session, so please enable the session state of SharePoint in web.config:
(1). add the element <add name="Session" type="System.Web.SessionState.SessionStateModule"/>.
(2). modify the pages element as <pages enableSessionState="true" enableViewState="true" enableViewStateMac="true" validateRequest="false" />.