Looked forever for this, even posted the question. I have the answer now.
Steps:
1. Choose the IPs that you want.
2. Make the custom template fragments:
mkdir -p /etc/e-smith/templates-custom/etc/pptpd.conf
3. Create the template fragment needed:
touch /etc/e-smith/templates-custom/etc/pptpd.conf/remoteip
4. Edit the fragment with your favorite editor and insert these contents:
remoteip <ip-range>
ip-range will be the range of IPs that you want to use. It must be in this format:
10.0.0.230-240 would specify IPs 230 through 240 are usable
5. Save the file and expand the template:
/sbin/e-smith/expand-template /etc/pptp.conf
6. Restart the pptpd service:
service pptpd restart
7. Test the VPN by making a connection and check your IP.
That's it