Hi,
You could purchase a laptop HDD caddy.
Most SSDs should fit into the caddy with the screwholes lining up.
Here is a link that shows how to remove the HDD from a T41 laptop. Just reverse the procedure.
http://www.laptopinventory.com/LaptopInventory.php/IBM/Thinkpad/T41/Hard%20Drive
Here is a link, from just one supplier, that shows what a caddy costs and looks like. There are a lot more suppliers if this one doesn't appeal to you. Just search online for Thinkpad T41 HDD caddy.
http://www.tmart.com/Hard-Drive-Cover-Caddy-for-IBM-Thinkpad-T40-T41-T42-T43_p94313.html
You may have to pack out the SSD a bit if it is thinner, to support it (even with the screwholes lining up) , so as to not place too much stress on the connectors. Any foam or rubber type material should be suitable.