Patrick Chung,
Upgrading IS from v4.6 to v6.1 is quite easy. I assume you have no ES component involved in the upgrade as per your post.
Just go through the release notes for all the changes between the two versions. Some of the built in java svcs have been deprecated in v6.x.
Also, there are major changes in developer functionality in v6.x; Again going through the Release Notes will help you.
Also, search thru wMUsers and you will see tons of information on the upgrade.
If you have any specific questions, feel free to let us know about it.
All in all, have the 6.x env set up and move the packages from v4.6 to v6; QA and make amendments if deemed necessary. (and go through v6 documentation)
Best of Luck.
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