Fletch is on the right track with this. First, everything you do with clearcase inside some view tag has to be 'exec'd out'.
So here is one complex way of getting around clearcase problem:
Have perl generate a simple 3 liner sh script, something like,

#!/bin/sh
/pathtocleartool/cleartool setcs -tag VIEWNAME CONFIGSPECPATH
...do things here...
[download]

Then, in your perl script, /cleartoolpath/cleartool setview -exec $shellscriptname VIEWNAME

This spawns a new process for each thing you do using clearcase exec, which is the documentation you need to look through.