Unfortunately the reporting assemblies are staticly referenced from OnTime Web, so there's no way to seperate the two in order to run in 64-bit mode.
IIS 7.0 supports running 32-bit and 64-bit app pools side by side on the same server, but for IIS 6.0 and below, the only real option is to install IIS on two different servers -- one for 32-bit applications and one for 64-bit applications. This is a fairly frequent problem given Exchange 2007's 64-bit-only requirement, so I gather this is MS's way of encouraging people to upgrade to Windows Server 2008 ASAP 
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