RPM has an option (–prefix) that allows users to install rpms in other directories than the default ones.
Packages that allow to be installed in other directories are called : relocatable

[root@localhost gcc]# rpm -qpi libxslt-1.1.24-4.fc11.i586.rpm | grep Relocations
Name : libxslt Relocations: /usr
[root@localhost gcc]# rpm -qi libxslt | grep Relo
Name : libxslt Relocations: /usr

So basically you can install this package in other directory.

[root@localhost gcc]# rpm -ihv libxslt-1.1.24-4.fc11.i586.rpm –prefix $PWD –force
Preparing… ########################################### [100%]
1:libxslt ########################################### [100%]
[root@localhost gcc]# ls
bin lib libxslt-1.1.24-4.fc11.i586.rpm share

For example gcc is not relocatable and installing it in an different directory is not allowd:

[root@localhost gcc]# rpm -qi gcc | grep Relo
Name : gcc Relocations: (not relocatable)
[root@localhost gcc]# rpm -Uhv gcc-4.1.2-33.i386.rpm –prefix=$PWD
error: package gcc is not relocatable