I hacked a green laser about a month ago, and posted here for help. What I've learned here and from other boards is echoed by flogged in the post above this one.
IR pumps for green lasers are multi-mode, and aren't really meant to be collimated.
Single-lens collimated IR lasers are commonly available. They start with a single-mode laser diode.
That said, many green lasers have three lenses:
1 - a crude collimator between the diode and the crystal
2 - an expander lens after the crystal
3 - a collimating lens at the tip.
The expander lens was catching the green output from the crystal, and making a relatively uniform green beam to the collimator.
If the expander lens is a small-orifice type, and if you can relocate it closer to the ir pump diode (like about where the crystal used to be), then it will still perform it's basic function, which is to convert a rough beam to something more usable for the collimator. The small orifice will block some of the beam. The lens will expand the rest onto whatever is in front of it.
Remove the green collimator, and replace it with a collimator from an IR module, and you may have something.
Aixiz sells a 980nm IR module for $12. It has a removable (threaded) acrylic collimating lens that will work for IR. I also bought a $2 glass collimator from them, and it was also capable of collimating the output from the IR module.
Good luck!