In addition to the resources you listed, these pages address some IBM-specific concerns and were helpful to me in installing FreeBSD 6.2, 6.3, and 7.0 on IBM T23, T41, and X22 laptops:
FreeBSD On Thinkpad T41p
FreeBSD 6.1 on T42
FreeBSD 5.x on T41 <---older but has some useful information
Good luck and I hope this turns out well for you. I am very happy with 7.0 on my T41 ThinkPad.