You can easily solve this with the SmartGit/hg GUI:
- open the log of the master branch
- right-click on the first revision from the time, you forked the main project and create a new branch from there
- switch into that branch in the left bottom corner with right-click
- cherry-pick the revisions you want to make a separate pull request and commit them as one commit
- push your new branch up on GitHub
- there you can create a pull request from just that branch
for the second pull request, you create a new branch and do the same with it