I installed sysrescd on an USB stick to resize a partition that had too little space on it. The hitch was that it was on an encrypted partition. This is the correct order of the commands that needed to be issued.
sda3 is the encrypted device systemvg is the name of the volume group lv_usr is the name of the logical volume
cryptsetup luksOpen /dev/sda3 crypt vgcreate systemvg /dev/mapper/crypt lvm vgchange --ignorelockingfailure -P -a y lvextend -L+2G /dev/systemvg/lv_usr e2fsck -f /dev/systemvg/lv_usr resize2fs /dev/systemvg/lv_usr