Well I have certainly used a IBM Thinkpad power supply to power my Empeg from.
check that the voltage of your Thinkpad P/S is within the allowable range for the empeg [empeg range is min. 11V to max of 16V and the IBM PS is pretty close to that upper limit].
Note: Some older thinkpads had a different PS with a higher voltage. Thoe Thinkpads I've used were all less than 3 years old.
Also check that the polarity of the Thinkpad PS output matches your empeg - that is centre pin positive, [ground is negative].
Other than that, your supply will work fine.
As far as a AC cord goes, well you don't say which country you live but IBM parts like this are pretty common if you look in the right place.
For those who don't know the IBM power supply has a smaller than IEC style socket on the PS and the socket is clover shaped i.e. it has 3 rounded 'pins' in the shape of a 3 leaf clover which means you can't take a normal IEC connector and make it fit [IEC's have rectangular 'pins' IBMs have round pins].
I don't know if any other laptop power supplies have a similar shape - most ones these days use a regular IEC style socket so any IEC cord for your power will do.
The only other device I've seen with the same type of cord is the Nokia M1122 ADSL modems we use here in New Zealand.
These are the same kind of plug so may be a suitable replacement source.
I do have a spare Thinkpad US style power supply AC cord [from my Thinkpad] [with a US plug on it (came with both local and US cords], I don't travel much so I don';t really need it and if I did travel I'd use a 'plug convertor' rather than the cable they supplied.
The US style plug could be replaced with a UK, European or whatever cord as required].
While the cable would be free - you'd have to pay the cost of me sending it to you - which would be about $5USD as least depending where you live and how urgently you want it.
I'd look at the main IBM support website [support.ibm.com] and locate the Thinkpad area and try and find the local [or closest] phone number to you for support and see what they charge for a replacement AC power cord.
Knowing IBM it will either be really cheap or really, really expensive.