This process is outlined in the K-base (somewhat). Here
Start by using a FTP program to upload a copy of your database dump. Just drop that file into he main directory that you see when you first log in. This is Behind the web-accessable area so it can't be downloaded by website visitors and saves a bit of extra typing.
Next you'll need to make sure that your user has shell access. By defult a user is set up as FTP only. Log into the Control Panel Click: Users> Users> Then click Edit across from the user name you want to log into Telnet with. Put a check next to "Enable ssh/telnet? " and click save changes. That user now has the access needed to log in.
Now, log into dreamhost via Telnet or SSH. Windows has a telnet program allready installed that will work Start> Programs > Accessories >Communication > Hyper Terminal. Or you can download a program called putty for a SSH connectio which is more secure.
To log in there, you'll need to know the machine you're hosted on here at dreamhost. You should have such information in your welcome E-mail I believe. For me it's Galage.dreamhost.com Then you log in with the user name / pass.
type in something to the effect of
mysqlimport -L -hHOSTNAME -uUSER -pPASSWORD DATABASE DUMPED_TEXTFILE
mysql -hHOSTNAME -uUSER -pPASSWORD DATABASE < DUMPED_TEXTFILE
fill in hostname, user password, etc with the correct informaiion. Also please note that things are case sensitive.