SEO Increase PageRank from 3 to 4

Have a .[login to view URL] website with a Google PageRank of 3. Want to raise that PageRank to 4 or higher as quickly as possible. This should be an easy job for a SEO expert. Conditions: - No Spam methods - You can't change the website. All optimisation must be offsite. - No Administrator Access to website provided - No outbound links/reciprocal links from the website provided - New back links need to be permanent, one-way and from different class-C IP addresses - No methods that will get our site blacklisted by Google or other search engines - No FFA, link farms, Pharmacy, Gambling, etc. Have already completed on-page optimisation for the site and submitted to directories. 50% of payment made by GAF once Page Rank 4 reached. Remaining 50% when PageRank 4 maintained for one month. No payment will be made if Page Rank 4 is not achieved. White hat techniques only. Please describe in your bid what techniques you will use.