Quoting itenerant
I've heard rumours that there is a 14 day entry permit for travellers coming from China through the Khunjerab pass - is this true? I am planning to cross on this and then try to extend it in Islamabad.
If not, care to share how one might "acquire" the Pakistani visa on the road? I think this involves a letter of invitation, proof of sufficient funds and onward travel etc etc (ie it is a right pain in the behind)...
Thanks, really appreciate any help i can get 
Well, you may not be able get the pass. It works the other way round and only for the people of northern areas of Pakistan. The people there get their pass with access only uptil Kashgar, not beyond.
As for you, you would definitely need to apply for a visa, plus if there is proof you are going to be traveling with a tour operator on the Pakistani side, you can easily get a visa. Though, I myself work as a manager at a tour company in Pakistan, but would not be able to post links or email addresses here.
If you need more help, I am here for your response,
Regards