Hi Tom,
You can create custom reports in any version of ITNM.
Keep in mind that in ITNM v3.x versions plus v4.1.1, we were using BIRT & Cognos (Hybrid) reports , where as in ITNM v4.2 we moved completely to Cognos and deprecated BIRT version. You can use BIRT designer to create custom reports for earlier versions, where as for new version, I haven't palyed much with Cognos - but you can read more @ http://public.dhe.ibm.com/software/data/cognos/documentation/docs/en/10.2.1/ug_cra.pdf
The reason for above URL is - Cognos 10.2.1 is bundled with TCR v3.1.
Having said all that, have you had chance to review Out-of-the-box reports of ITNM v4.2 ? Is there a specific need that isn't fulfilled by these reports. Also, feel free to create new enhancement request to fill such gaps @ http://www.ibm.com/developerworks/rfe/?BRAND_ID=90
All the best,
Krishna.